Sciencemadness Discussion Board - Bank card – gold plated

Bank card – gold plated

vmelkon - 28-11-2020 at 18:56

Hello guys,
This is just information for those who want to do gold extraction from electronics.

My bank card has one of those integrated chips.
I cut out the chip part since I was curious if the golden contacts were copper, brass or gold.
I put the chip part in H2SO4 (maybe conc. 30%) and added NH4NO3.

It was bubbling slowly. The liquid became blue-green. There were also a very thin golden foils floating around.
I think the stuff is gold plated.

I’ll try to upload a picture.

itsallgoodjames - 29-11-2020 at 14:42

That's pretty much to be expected. There's a layer of copper adhered to the fiberglass board, with a layer of nickel than a thin layer of gold on top of it. The purpose of the gold is to not corrode. If copper or brass, over time the contacts would corrode and no longer be electrically conductive. I'm not sure what exactly the nickel is for, if someone could educate me on that I'd be delighted. The solution is probably a mixture of copper and nickel sulfates and nitrates.

paulll - 30-11-2020 at 14:21

Supposedly the copper will diffuse into the gold and eventually render the plating useless if they're in direct contact, so the copper's nickel-plated first as a barrier to that.

itsallgoodjames - 1-12-2020 at 09:03

Huh, that's an interesting reason. I'd have never thought that would be why they put a layer of nickel. I'd imagine silver would work too, though it'd get expensive. I guess nickel would work decently, while being cheaper. I guess that's why they use it

vmelkon - 4-12-2020 at 17:15

I was surprised because it is just a bank card and I assume that they are intended to be used for 5 to 7 y.
What about Atari 2600 and Nintendo cartridges? Don’t these just use the PCB copper?

I know that after 22 y, Nintendo cartridges tend to have problems and require some scrubbing the oxide off.

itsallgoodjames - 8-12-2020 at 09:03

My guess is that it's now possible to get a thinner layer of gold, so it's become more cost effective to use gold, and not have to worry about corrosion.

Also, are you sure they use copper? All the cartridges I have for the commodore machines use a plating of either silver or nickel, I can't tell which. They have tarnished in a similar way to the silver coins I own, so I'm leaning towards that.

vmelkon - 8-12-2020 at 19:26

Quote: Originally posted by itsallgoodjames

My guess is that it's now possible to get a thinner layer of gold, so it's become more cost effective to use gold, and not have to worry about corrosion.

Also, are you sure they use copper? All the cartridges I have for the commodore machines use a plating of either silver or nickel, I can't tell which. They have tarnished in a similar way to the silver coins I own, so I'm leaning towards that.

Nickel plating is a good idea. Canadian coins, such as the 10 cent and 25 cent were pure nickel and they remain shiny to this day. I think they are just solid iron with nickel plating now.
Look at your utensils and kitchen sink. They stay shining for a long time.

I am not 100% sure whether NES cartridges are just copper or copper plated with gold but why else would scrubbing it fix them up?

itsallgoodjames - 9-12-2020 at 08:07

Dust buildup. If something sits in storage for 30 years, the dust tends to form a crust that interferes with the connection. This is compounded by the fact that a lot of these cartridges have been stored in sheds, where the humidity and temperature changes can get the dust to really stick. This is all from first hand experience getting old computers and video game consoles back up and running. It's the dust.

Edit- I know about the coins. That's the way I get most of my nickel for nickel complexes.

[Edited on 9-12-2020 by itsallgoodjames]