over plated aerospace boards??
- Thread starter jrmycooke
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Very nice, thick foils. Good score!
Is it just the light or is there still nickel on some of those foils?
They almost look TOO thick. Will a strong magnet pick them up? What did you use to dissolve the copper - AP or nitric?
A
Anonymous
Guest
GSP is right.I have processed my share of nasa material,and while the plating is usually thicker,it doesn't look like that.Unless you ran them in just Hcl with no form of oxidizer,or agitation.And even then,they most certainly have base metals still on them.However you still may have a very surprisingly nice yield when it is all done.
A
Anonymous
Guest
I do not know how these were recovered,but since we haven't heard from Jeremy since yesterday,I wanted to speculate.Blowing up the picture,it almost looks as though there is still masking on the foils giving them the discolored look.However they very well may have been "peeled" off since some of the pieces(click on the picture below) look curled,as though they had been removed with some type of blade.
Bear in mind,this is just speculation.Until Jeremy chimes back in,we don't know for a fact.
Bear in mind,this is just speculation.Until Jeremy chimes back in,we don't know for a fact.
Attachments
Sorry members, early bedtime last night. Regular a/p run, leeched for over two weeks because this stuff just wouldn't separate. I pulled the board, rinsed and used a lock out tag out card to scrape the board and tweezers to pull off the long foils. There's wasn't any coating that I could see visibly, but the areas not attacked by the solution I gave a good scratch and still no reaction. This was my first time processing a "mil-spec" material and have never encountered such a long leech.
That last photo helps. I was confused because I couldn't picture that foil coming from a circuit board. What you have is circuit board trim. The circuits have been cut out. I would estimate about 80-90in2 of plated area on one side of each sheet.
The trim is unusual in that the design wasted a lot of gold. Probably 90% of that area could have easily been masked off and left unplated. This leads me to believe that it is (a) a trial run, (b) a small one-time run, or (c) for the military or NASA and no one involved gives a s**t what it costs.
If (c), it could be quite thick. There are many big pieces and that could very well be due to the gold thickness. In order to get to the copper, the acid normally penetrates though microscopic pinholes and stress cracks in the gold plating. However, with thicker gold, these holes an cracks tend to seal and prevent the gold from getting to the copper. That sounds like a good possibility of why it took so long to process. When at some threshold of thickness, the only way the acid can get to the copper is from an occasional stress crack or flaw, here and there, in the gold. I have seen 30 microinch gold that remained in one (or, just a few) piece after leaching with nitric but, usually, it would take about 50-100 microinches to do that.
---At 80in2 plated 30 microinches (micro") thick, there would be 0.76g of gold
---At 50 micro", there would be 1.26g
---At 100 micro", 2.52g
---At 200 micro", 5.06g
There is a possibility that the reason your foils aren't broken up is because there is something else present that is holding the foils together. That could be nickel or a clearcoat. Nickel could be dissolved in hot 50/50 nitric. A clearcoat could be removed by incineration. I doubt if it's a clearcoat, though, since I can't see them cutting out the circuits after clearcoating. Try a little bit of the foil in some hot nitric and then compare that gold with rest of it, side by side. Use good lighting and a loupe, if you have one.
The trim is unusual in that the design wasted a lot of gold. Probably 90% of that area could have easily been masked off and left unplated. This leads me to believe that it is (a) a trial run, (b) a small one-time run, or (c) for the military or NASA and no one involved gives a s**t what it costs.
If (c), it could be quite thick. There are many big pieces and that could very well be due to the gold thickness. In order to get to the copper, the acid normally penetrates though microscopic pinholes and stress cracks in the gold plating. However, with thicker gold, these holes an cracks tend to seal and prevent the gold from getting to the copper. That sounds like a good possibility of why it took so long to process. When at some threshold of thickness, the only way the acid can get to the copper is from an occasional stress crack or flaw, here and there, in the gold. I have seen 30 microinch gold that remained in one (or, just a few) piece after leaching with nitric but, usually, it would take about 50-100 microinches to do that.
---At 80in2 plated 30 microinches (micro") thick, there would be 0.76g of gold
---At 50 micro", there would be 1.26g
---At 100 micro", 2.52g
---At 200 micro", 5.06g
There is a possibility that the reason your foils aren't broken up is because there is something else present that is holding the foils together. That could be nickel or a clearcoat. Nickel could be dissolved in hot 50/50 nitric. A clearcoat could be removed by incineration. I doubt if it's a clearcoat, though, since I can't see them cutting out the circuits after clearcoating. Try a little bit of the foil in some hot nitric and then compare that gold with rest of it, side by side. Use good lighting and a loupe, if you have one.
etack
Well-known member
Just a thought but in this case could he de-plate them in a cell faster?
Eric
Eric
etack said:
Certainly, assuming there is no clearcoat present.
