# AP having no effect on gold traced board



## cvillan (Jul 7, 2012)

For the past couple weeks I've been running a few batches of mixed electronic scrap in my AP solution. One board has been giving me some trouble. It was a late 80's 16bit ISA video card with gold plated traces. I depopulated the board and stripped off the solder mask and threw it in with the first batch. By the time everything else had processed this one card had almost all its gold still attached. It was just a bare PCB with traces. I put it back in to process with the next batch and again, everything else finished and this card had barely any change. A very small fraction of the gold traces had come off, perhaps 5% at most. The rest remains stubbornly attached. I have a couple pictures of it. Anyone have any idea whats going on. I cant think of anything the gold could possibly be plated to that would have no reaction in AP.


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## Geo (Jul 7, 2012)

cut it into smaller pieces and put in a container and try hcl/Cl on the one piece. it will bring the foils off.


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## Marcel (Jul 7, 2012)

The AP did have an effect on your boards. All the vias have been washed away. Sometimes, some PCB producer use "exotic material" for the layer underneath the gold. I guess your Copper is already gone, but still "glued" to the board by some uncommon layer.
I find Geo´s proposal very smart and worth a try.


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## mjgraham (Jul 7, 2012)

Kind of looks like to me there may be a clear coating over it.


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## NobleMetalWorks (Jul 7, 2012)

Did you remove the soldering mask?

Soldering masks may prevent the gold from being foiled off. If you didn't remove the soldering mask, you might have a difficult time coaxing the soldering mask of. At this point, because you already started processing the PC boards, you should probably take Geo's advice. By cutting into small pieces it makes it easier for a solution to get at, or underneath, the gold.

I did about the same thing with plastic chip packages fairly recently. I shredded them into small enough pieces that my solution could get at the internal structure from the sides, and it worked awesome.

Scott


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## maynman1751 (Jul 7, 2012)

SBrown said:


> Did you remove the soldering mask?
> 
> Soldering masks may prevent the gold from being foiled off. If you didn't remove the soldering mask, you might have a difficult time coaxing the soldering mask of. At this point, because you already started processing the PC boards, you should probably take Geo's advice. By cutting into small pieces it makes it easier for a solution to get at, or underneath, the gold.
> 
> ...



Hey Scott! (I got it right this time 8) )


> I depopulated the board and stripped off the solder mask and threw it in with the first batch.


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## NobleMetalWorks (Jul 7, 2012)

maynman1751 said:


> SBrown said:
> 
> 
> > Did you remove the soldering mask?
> ...



Too funny, I am going to copy and paste names from now on so I don't mess any up.

If you look at his pictures, the top one with that hand wearing the glove. Look to the right hand side, you can see an area of the board that has nothing on it at all, it's totally bare, right on the right hand edge. If you look just to the left of that bare spot, you will see a shiny reflective surface. I believe that is some type of soldering mask.

Sometimes on older electronic boards they used a shellack type of material that is more difficult to remove than the normal soldering mask you usually come across. I had some boards with really heavy gold solder like what I posted below. These boards are all late 1970s. If you look, you can see the heavy soldering mask.

Here are a couple boards with the type of soldering mask I am describing.











You can see the solder mask I am talking about on this board, it was applied after components were soldered to the board, when I removed some of them I took this picture go show how the shellack was applied.






Here is a board that I had to process a second time with the lye past, because only part of the mask was removed. If you look at the bottom left, you will see the part that wasn't removed, and the difference between the parts that the mask was removed, and the parts that were not.






I ended up making lye paste to brush on these boards in order to get the soldering mask off. It was just simply too thick. Here is a cleaned board, what it looks like after the soldering mask is removed.






Scott


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## maynman1751 (Jul 7, 2012)

I know what you are talking about. I used to work for Goodyear Aerospace and did electronic assembly on military components. We used a variety of masks depending on the application. Your talking about anything from torpedoes to cruise missiles to nuclear missiles. The boards had to stand up to some pretty extreme environments and temp changes and reliability was key.....needless to say!


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## rshartjr (Jul 8, 2012)

I've been lurking for a little while as I have begun to take an interest in e-waste PM recovery, but have not, yet, had anything to add. Until now: I used to be a Naval avionics technician and was qualified in micro-miniature solder repair. I don't mean to knit-pick, but what you are dealing with is not "solder mask."

Solder mask is applied after the printed wiring board is first etched to prevent solder flow beyond the mounting holes/pads as discrete components are installed during production.

That shiny substance that is applied after the circuit card assembly is completed is called "conformal coating." It prevents dirt and moisture from playing havoc with your energized gear. Most are lacquer or varnish-based and dissolve quite readily with a liberal application of isopropyl alcohol and some light scrubbing.

There is an unclassified Navy technical manual you can search online entitled NAVAIR 01-1A-23. There is a section within that describes how to identify and safely remove the various types of coatings, from the lacquers and varnishes, to the epoxy and silicone RTV coated cards.

Scott


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## NobleMetalWorks (Jul 8, 2012)

Thanks for the information, having a hard time finding the actually document though.

If anyone finds it, could you please post a link here?

That's one of the many reasons this forum is so awesome, where else would you find the quality of information we do here?

Scott


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## jimdoc (Jul 8, 2012)

SBrown said:


> Thanks for the information, having a hard time finding the actually document though.
> If anyone finds it, could you please post a link here?
> 
> Scott



Is this it;

http://www.tinker.af.mil/shared/media/document/AFD-070314-040.pdf


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## NobleMetalWorks (Jul 8, 2012)

jimdoc said:


> SBrown said:
> 
> 
> > Thanks for the information, having a hard time finding the actually document though.
> ...



I downloaded that same pdf because the link I hit looked like it was for the document (-23 not -1) but it ended up being wrong and only making reference to the -23 document.

Thanks for trying though. I am curious how the military manual will say about removing the conformal coating. I am not so sure I want to play around with IPA or Propanol, or even have it around in quantity at least until I move into a building. I am already keeping acids and chemicals in my garage that I'm not comfortable with, and having to keep it air conditioned. I used to be a Mechanic for UAL and still have friends there that use different methods to strip material off aircraft parts, I think I'm also going to pick their brains and see what I come up with. Although I have to admit, the lye solution has done very well for me.

Scott


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## rshartjr (Jul 8, 2012)

I used to be able to access it online, but that old link is gone. It is also known by the "Technical Order" number assigned to it by the Air Farce... er... Chair Force... um... I mean, _Air Force_ (Whatever) or "T.O." Those weirdos call it: T.O. 00-25-259.

The following link appears to be free. They only seem to want you to register with their site (Which I, personally, would never do):

http://www.imarksweb.net/book/navair+01+1a+23+pdf/

The following two, which I am in *NO WAY* endorsing, want your hard-earned cash in order to allow you to download a PDF:

http://www.chqsoftware.net/product_info.php?cPath=119_145&products_id=2887

http://www.newportaero.com/home/manuals/technical_orders/browse/___175/to.html?sort=part_number

Good luck!
Scott


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## maynman1751 (Jul 8, 2012)

rshartjr said:


> I've been lurking for a little while as I have begun to take an interest in e-waste PM recovery, but have not, yet, had anything to add. Until now: I used to be a Naval avionics technician and was qualified in micro-miniature solder repair. I don't mean to knit-pick, but what you are dealing with is not "solder mask."
> 
> Solder mask is applied after the printed wiring board is first etched to prevent solder flow beyond the mounting holes/pads as discrete components are installed during production.
> 
> ...



That's the term that I was looking for, conformal coating! It's been over 20 years since I worked at Aerospace and had forgotten some of the terminology. Thanks for the reminder. It's all coming back now........


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## rshartjr (Jul 8, 2012)

maynman1751 said:


> rshartjr said:
> 
> 
> > I've been lurking for a little while as I have begun to take an interest in e-waste PM recovery, but have not, yet, had anything to add. Until now: I used to be a Naval avionics technician and was qualified in micro-miniature solder repair. I don't mean to knit-pick, but what you are dealing with is not "solder mask."
> ...



Glad I could help!
Scott


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## cvillan (Jul 9, 2012)

Wow. Lots of responses. I double checked the boards and the solder mask is fully removed. I'll be using the HCL-CL idea from Geo tomorrow to finish off this board. As for the "Exotic Material," any idea if its something worth recovering. I took apart a few more machines and have 5 identical cards I'll be processing this week.

Oh, Scott, those boards are awesome. Wish there was somewhere around here I could get my hands on some. I should probably talk to some of my friends at the GE plant up the street and see if there is a way to get my hands on their rejected boards.


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## NobleMetalWorks (Jul 9, 2012)

The particular boards I posted in this thread actually came from a guy who was down on his luck, then his real birth father, whom he never knew, passed away and he was the only heir. He ended up with a warehouse full of old equipment from the 50s-70s. Evidently his father bought equipment and just held onto it. So he's breaking it down, slowly, enjoying life and making a decent living. He says he has enough to keep him busy for the rest of his life, and he has been steadily supplying me with material. But so far as the I-Waste is concerned, GE sounds like it should be a gold mine to me. Just ask for their asset recovery department and then ask to speak with the person in charge of reclaiming value from their processing waste.

G.E. is also a government military contractor, if you luck out and G.E. is manufacturing anything for the military at the plant close to you, there might even be a chance that the material would be mil-spec which means more precious metals for you.

Scott


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## BAMGOLD (Jul 9, 2012)

GE where? Salem? I use to work for GE Wind...


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## cvillan (Jul 10, 2012)

Geo:
Worked great. Thanks for the pointer.
Anyone have any idea what the magical mystery metal the gold was plated to might be?

BAMGOLD:
GE Fanuc http://en.wikipedia.org/wiki/GE_Intelligent_Platforms just outside Charlottesville Virginia

Its not even a mile from my house. I talked with a friend there and he let me know he'd find me the contact info I need. He did say he knew they wouldnt sell to an individual though. Looks like I need to dig up my LLC books I never read.


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## etack (Jul 10, 2012)

is this the book Avionic cleaning and corrosion prevention/control: organizational and ...
By United States. Dept. of the Army

http://books.google.com/books?id=7Xw-AAAAYAAJ&pg=PR15&lpg=PR15&dq=NAVAIR+01-1A-23&source=bl&ots=TPBafee_FN&sig=WeHksijGLH4jZf8Qan0rs6bZhaQ&hl=en&sa=X&ei=OXn8T9yFGunp0QHyi-XEBg&ved=0CDMQ6AEwAA#v=onepage&q=NAVAIR%2001-1A-23&f=false


This is the wrong book sorry but the document can be found as T.O. 00-25-259 this is the Air Force version http://www.robins.af.mil/shared/media/document/AFD-091005-067.pdf

Eric


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## rshartjr (Jul 10, 2012)

etack said:


> is this the book Avionic cleaning and corrosion prevention/control: organizational and ...
> By United States. Dept. of the Army
> 
> http://books.google.com/books?id=7Xw-AAAAYAAJ&pg=PR15&lpg=PR15&dq=NAVAIR+01-1A-23&source=bl&ots=TPBafee_FN&sig=WeHksijGLH4jZf8Qan0rs6bZhaQ&hl=en&sa=X&ei=OXn8T9yFGunp0QHyi-XEBg&ved=0CDMQ6AEwAA#v=onepage&q=NAVAIR%2001-1A-23&f=false
> ...



Sorry, but both of those links only reference the proper manual. The three links I provided earlier were for the actual one, I just haven't been able to find a site with free access.

Scott


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