Step by step instructions for AP processing circuit boards

[Taleeho]

I have many hundreds of AMD CPU’s with matrix of plated pins about 1 1/2 mm long on face. How best to remove and use AP? Thinking about placing them on a hot griddle then scraping pins off. Would tin from solder interfere with dissolving the Cu out?

 

[Yggdrasil]

I have many hundreds of AMD CPU’s with matrix of plated pins about 1 1/2 mm long on face. How best to remove and use AP? Thinking about placing them on a hot griddle then scraping pins off. Would tin from solder interfere with dissolving the Cu out?

Remove the Tin first with HCl, then go to AP or Nitric.

 

[anachronism]

If you use HCl to remove the Tin you'll find that the pins will fall off themselves. Are you talking about the green fibre ones with the heatsink attached?

 

[haveagojoe]

I used to use gouging rods for burning out bad welds, a carbon rod coated in copper, to form an electrolysis cell. Removing enough copper to still be AP for reuse.

I'm interested in this idea as a way to save on HCl and keep the volume of solution from growing ever larger.

If the acid is used on magnetic e-scrap pins, it will create Iron Chloride as well as the Copper Chloride. I'm wondering if the electrolysis would remove both Iron and Copper from the solution together? I imagine that the metal which collects on the cathode would be a combination of Iron and Copper (I'm not sure if we can call it an alloy?)

 

[Yggdrasil]

I'm interested in this idea as a way to save on HCl and keep the volume of solution from growing ever larger.

If the acid is used on magnetic e-scrap pins, it will create Iron Chloride as well as the Copper Chloride. I'm wondering if the electrolysis would remove both Iron and Copper from the solution together? I imagine that the metal which collects on the cathode would be a combination of Iron and Copper (I'm not sure if we can call it an alloy?)

You could just run the AP until the surplus Copper precipitates out as Copper (I) Chloride.
It will become a whitish paste insoluble in water.
Filter it out and add some more HCl and water to it and go on.
The Iron Chloride will eventually foul it though.

 

[haveagojoe]

You could just run the AP until the surplus Copper precipitates out as Copper (I) Chloride.
It will become a whitish paste insoluble in water.
Filter it out and add some more HCl and water to it and go on.
The Iron Chloride will eventually foul it though.

Yes that's what I do at the moment but HCl is £15 for 5 litres now in the UK and I'm just accumulating more AP solution than I need.

What do you mean by "fouling" the solution? As far as I understand Iron is not a big deal since Ferric Chloride also etches Copper; the solution seems to keep working... I thought AP reaches the end of its useful life when it becomes loaded with nickel, zinc etc?

I'm just interested since it seems like quite a neat way to rejuvenate the AP without having to filter since Copper (I) Chloride is so fine it filters rather slowly.

Also since Ferric Chloride has 3+ ions while Cupric Chloride has 2+, wouldn't it remove 3 parts Iron to 2 parts Copper onto the cathode? I'm thinking this would help to bring balance of the remaining mixture back towards a Copper Chloride etch rather than Iron Chloride.

Maybe my understanding is a bit hazy, it's a long time since I did the equations at school..

 

[Yggdrasil]

Yes that's what I do at the moment but HCl is £15 for 5 litres now in the UK and I'm just accumulating more AP solution than I need.

What do you mean by "fouling" the solution? As far as I understand Iron is not a big deal since Ferric Chloride also etches Copper; the solution seems to keep working... I thought AP reaches the end of its useful life when it becomes loaded with nickel, zinc etc?

I'm just interested since it seems like quite a neat way to rejuvenate the AP without having to filter since Copper (I) Chloride is so fine it filters rather slowly.

Also since Ferric Chloride has 3+ ions while Cupric Chloride has 2+, wouldn't it remove 3 parts Iron to 2 parts Copper onto the cathode? I'm thinking this would help to bring balance of the remaining mixture back towards a Copper Chloride etch rather than Iron Chloride.

Maybe my understanding is a bit hazy, it's a long time since I did the equations at school..

I think the issue is that Ferric Chloride do not rejuvenate by the Oxygen (air bubbling) as Cupric Chloride do.

 

[Shark]

Don't filter it, allow it to settle and decant the solution from the CuCl1. Filtering is not always the best solution. In my method, I run material until the CuCl1 builds up a pretty good volume. Stop the air pump and allow it to settle. Decant into the next bucket, and start it up again. The solids I collected are now cleaned by adding fresh HCl and dissolve that CuCl1, then collect the sludge for processing. The real trick is setting up the '"AP" bucket to speed the process. The way I use it, there is a loss of volume more than usual so adding a little extra HCl is often needed to aid dissolution as much as to keep a working volume. It can also use waste AR in much the same manner, which I prefer, as I get extra use from the acids, also still collecting some pgm's while reducing the waste volume for disposal.

 

[haveagojoe]

I think the issue is that Ferric Chloride do not rejuvenate by the Oxygen (air bubbling) as Cupric Chloride do.

Aha yes of course. Well that would make my question more interesting; if we can get the Iron out by electrolysis it could really help.

Don't filter it, allow it to settle and decant the solution from the CuCl1. Filtering is not always the best solution. In my method, I run material until the CuCl1 builds up a pretty good volume. Stop the air pump and allow it to settle. Decant into the next bucket, and start it up again. The solids I collected are now cleaned by adding fresh HCl and dissolve that CuCl1, then collect the sludge for processing. The real trick is setting up the '"AP" bucket to speed the process. The way I use it, there is a loss of volume more than usual so adding a little extra HCl is often needed to aid dissolution as much as to keep a working volume. It can also use waste AR in much the same manner, which I prefer, as I get extra use from the acids, also still collecting some pgm's while reducing the waste volume for disposal.

Yes decanting and settling would be better for getting the CuCl1 out. I might have to alter my setup a bit though as currently I just use 5 litre plastic water bottles rather than buckets, the source material just sits on the bottom of the bottle so it gets mixed up with the CuCl1. Probably the answer would be to decant through a sieve to separate the source material from the CuCl1, I have been thinking about that.

I probably ought to use a perforated bucket to hold the material off the bottom inside another bucket like everyone else but I just got used to doing it this way as the bottles are so easy to use and handle. I can pour the solution rather than syphoning, I can see through the side to tell what's going on, and also I can put the lid on and give it a shake if I need to. Perhaps I can just decant into another bottle to allow the CuCl1 to settle. But with my method I get very little loss of volume so I think I would still have the problem of using more and more HCl and my solution growing over time. I will try decanting and see how it goes.

 

[Shark]

Look into air lift pumps. I use small ones in my AP and waste stream buckets. They work much better than pumping air into them.

 

[haveagojoe]

Look into air lift pumps. I use small ones in my AP and waste stream buckets. They work much better than pumping air into them.

Interesting, I can see they would enhance circulation of liquid.
In fact at one point I may have accidentally created a similar effect which caused a small spillage- I use a piece of PVC pipe to hold my bubbler tube at the bottom of the acid; when I let end of the bubbler tube slip back up inside the PVC pipe it resulted in acid being pumped up the tube and out of the top onto my hand.
Now perhaps if I cut a hole in the side of the tube halfway up I could make a crude airlift pump in the same fashion. Maybe I will experiment with this idea.

 

[haveagojoe]

air lift pumps

Update: it works! Fantastic!

The PVC pipe is about 1/2 inch internal diameter; I drilled a 1/2" hole in the side about 5 inches up from the bottom of the pipe, then inserted the bubbler tube from the top of the pipe all the way til it's just short of the bottom of the pipe, placed the bottom end of the pipe in the acid solution with the drilled hole above the surface, and it does indeed airlift the solution up the pipe and out of the drilled hole! It doesn't have a great deal of pressure, it's just dribbling out with lots of bubbles (the HCl I use is brick cleaner which has some kind of soapy foaming agent in it) but I think it will be adequate to move the solution around.

Thanks! This was an easy and satisfying upgrade to my setup which I think will improve the aeration and circulation quite a bit. It also has the advantage of being a bit quieter.

 

[Yggdrasil]

Update: it works! Fantastic!

The PVC pipe is about 1/2 inch internal diameter; I drilled a 1/2" hole in the side about 5 inches up from the bottom of the pipe, then inserted the bubbler tube from the top of the pipe all the way til it's just short of the bottom of the pipe, placed the bottom end of the pipe in the acid solution with the drilled hole above the surface, and it does indeed airlift the solution up the pipe and out of the drilled hole! It doesn't have a great deal of pressure, it's just dribbling out with lots of bubbles (the HCl I use is brick cleaner which has some kind of soapy foaming agent in it) but I think it will be adequate to move the solution around.

Thanks! This was an easy and satisfying upgrade to my setup which I think will improve the aeration and circulation quite a bit. It also has the advantage of being a bit quieter.

Same principle is often used for cementing, then with a larger diameter outer tube with holes and a Copper piece inside.

 

[Shark]

This what mine looks like when breaking down material. To reduce volume quicker raise the pump in such a way that it drops with a splash from the bottom