Identifying Gold in Circuit Boards

[Davros42]

Hello Everyone!

I am new to extracting gold from circuit boards and could use a little help. Sorry if this has been covered before, but I haven't been able to find what I need, even though it seems I have scoured the internet. I work in the electronic security industry and often have bad or useless circuit boards to get rid of. I take most of them to the scrap yard because I know they don't contain gold, but have been saving the ones I suspect do. I've watched some tutorials online and one suggested that if you compare the color of something you suspect is gold to something you know is gold, and it matches, it probably is. I don't know if I quite trust this and would hate to go to a bunch of effort to find out it was wrong. I have attached a couple of images of typical circuit boards I believe to have gold, and circled what I believe to be gold with a reference number. If someone could point me in the right direction, I would greatly appreciate it. Thanks!

 

[g_axelsson]

Welcome to the forum!

This topic has been covered a lot of times on this forum, spend some time to browse the threads in this part of the forum.

On your pictures the 1A is gold plated, reverse plating cell is recommended as there are so much base metals compared to gold here.
2A, 3A and 2B is gold plated, probably with ENIG, which is really thin.
1B I would doubt, no reason to plate what I suspect is antennas. A drop of nitric acid dissolves the base metal below any gold plate and you can see if there are any gold flakes coming off.

Check the black contact on the first picture, if yellow it's gold plated, silvery is tin plated.
Other good sources of gold is IC:s with internal bond wires, especially BGA capsules with plastic top.

Göran

 

[goldsilverpro]

Find better scrap.

 

[patnor1011]

I agree with GSP. Next to nothing of value when weight of board is considered.
There is also little bit of gold in contacts right between 1A and 2A.

On the second picture there should be one or more IC which will have more gold in bonding wires than plated contacts you circled on pictured side.

 

[Davros42]

Thanks so much for your help, I really appreciate it. As far as finding better scrap goes, I come by these for free as a part of my job and I don't have the time or money to invest in searching for something better, so they will have to do. I just don't want to throw them away and am interested to see if I can get more value from them by extracting the gold myself than taking them to the scrap yard. I've been collecting them for about a year and have just started breaking them down for refinement.

Based on what I have learned so far from different websites and tutorials, I'm separating them into two piles, one for PCBs and one for plated connectors and such. On the pcb batch I will use the AR method and on the plated stuff, the reverse electroplating method. At least that's the plan as of now. I'm still a ways from doing either of them yet since I've got a huge tub of them to break down, but I'm hoping to make a summer project out of it. I'm going to take a closer look at lazersteve's stuff. thanks again!

 

[solar_plasma]

one for PCBs and one for plated connectors and such.

the keywords for your search are "fingers" and "pins"

 

[wokaway]

i would take the mlccs for pd though

 

[PlainsScrapper]

In the first picture below the 3 capacitors, there is a small rectangle labeled with an X next to it. I suspect that is an oscillator, which should have some gold inside. Crack it open and see. Might have gold! 8)

 

[AndyWilliams]

Good Grief, I can barely see the markings because they are in red!

 

[Anonymous]

Good Grief, I can barely see the markings because they are in red!

Try this one Andy *winks* 8) 8)