Gold plated military Mother boards

[justme2]

I know Mother board processing has been discussed ad nasium to some of you. That said, these are so beautiful I have to ask.
Last year in one of the shipments from my primary customer, a Military contractor, I received one huge (600 lb) IBM server. When I opened it there were two mother boards and to back plains.

Each board is 18x16, I believe them to be early 80ish, each weighs about ten lbs populated. The two mother boards are populated with one large, four medium and 8 smaller (1 inch) old style IBM white ceramic Processors.

What is astounding to me, after processing hundreds of servers over the last two years, (over 14,000 lbs last year), these are the only MBs I have come across that are plated top to bottom, side to side with gold and it appears to be thicker then any other I have seen.

Ok to the point, you already know whats coming.

Is there a way to de-plate these boards with out incineration or, shredding. It dosen't have the blanket solder mask epoxy except in a few small places. The green coating comes off with a small brass brush.

I have processes some other old huge ribbon connectors with gold plating on the plastic harness that holds 5 connectors together. They have a dark brown glue substance between the copper and gold plating that makes clean up a tedious task but are doable. Any Ideas ?

The total plated surface is 288 sq inches plus the 13 processor seats and huge numbers of pins.

 

[GOLDbuyerCA]

PM sent, i got the bug. Cheers.

 

[nh6886]

I would think you could depopulate with HCl then strip the boards with AP solution and a bubbler.
I would love to see a picture of these.

John

 

[justme2]

Been trying to get my son to teach me pictures but, he's 20, nuff said.

 

[Captobvious]

Personally I would go with a heat gun to depopulate, HCL baths I've found to be hit or miss and given how pretty these boards are apparently a little more patience I think would be in order. Using lazer steve's method for killing the solder mask, he has a video on just this but be careful! Hot caustic soda is NOT something to take lightly!

 

[rickbb]

Depopulate with a heat gun or hot sand bath, then soak in HCL to dissolve any remaining tin solder. (Keeps the AP cleaner that way.)

If you see lots of gold then I'd strip the solder mask with hot, 20% NaOH. I've used it as low as 5% at 170F it just takes longer. With that much gold on it, I'd bet there more hiding under the mask.

Then strip the gold foil with the AP process as normal.

 

[justme2]

thanks guys. I will try to get pictures this week end.

 

[justme2]

Update:

I cut a 2"x5" piece off the board and scraped the un resined green mask off revealing the gold plate. I put it in my hcl/ho2o bubbler after 2 days the flakes came off in a nice sheet.

I then noticed the plating covering most of the board were tiny squares of gold foil in small squares had not all come away from the board, so, I left it in for 2 more days and went to another project.

I came back yesterday to find all signs of gold gone, completely dissolved. The solution was a medium to light Emerald green.

Any one else had this happen.

I did learn one lesson. I decanted my solution into my 5 gallon container of used A/P to recover expected foils. I should have decanted into a separate container and will in the future.
I should have

 

[cmiller92]

Considering you used a new solution of AP, maybe there is not enought copper. If you put more copper into the solution it will disolve and displace the gold in the solution, which will cement out as a black powder.

Just my two cents

 

[justme2]

Thanks:

I have about 4 gallons of A/P solution, dark emerald green. Can I use copper pipe to drop the PMs from this solution ?

 

[Geo]

How much peroxide did you use? 3% peroxide is hardly strong enough to dissolve thick plating in a short period of time much less over an extended period of time. The free oxygen in hydrogen peroxide is released fairly quickly in the presence of acids and a material that can be oxidized.If you have even one drop of the original solution or even residue in the bottom of the container that you can hydrate with a few drops of hcl, test it with stannous chloride to ensure you have gold in solution. The gold plating on boards that are not connector pads will be really thin. It is possible that the foils broke apart and are so finely divided, it could be hard to see.

 

[nh6886]

Justme2,

I have had gold plating break up like Geo's suggesting, however I was able to recover it by doing the following;
1. I filter the AP through a glass fiber filled filter tube
2. Wash with alternating HCl and hot (boiling) water until clear.
you can save these washes to reuse to depopulate with by dropping lead with a little H2SO4.
3. Then use the solvent of choice (I use HCl/ bleach in this case) you can pour this back through the filter as needed to keep your volumes down then rinse the filter clear with water.
4. Add a few drops of H2SO4 let settle then decant your solution and if you think you have any excess Cl (I doubt it) heat until the strong bleach smell stops.
5. Drop the gold with your favorite precipitant and wash with one of the many methods shown here on the forum.

You don't have the advantage of being able to incinerate the powders with this method but if you are going to double refine anyway, I find it a fast and reliable way to recover fine particles.
I test ALL my solutions with stannic, whether they are wash water or pregnant solutions that way I'm not looking for my material later :roll:

This method works well for me but If anyone knows a reason this shouldn't be done please share your thoughts.

Be safe and have fun
All the best,
John

 

[justme2]

thank you all. Turns out George was right some of the gold became invisible.

I filtered the solution and removed the visible flakes and saved the solution. Rather then the usual emerald green the solution was nearer the yellow spectrum.

I have saved the solution. It tests positive for Au, Should I now treat that solution with SMB in an attempt to drop the AU.