The slow way. Plated boards and pins

Does this sound like everything will work properly? I haven't refined anything in a while, so I'm just making sure I still know what I'm doing.

I'm not worried about how long it'll take.

I'm not using a bubbler or H2O2. Just HCl by itself.

If I file off a bit of old green copper from a buss bar/pipe an put the filings into HCL, it'll make CuCl2. "The copper I'm using was clean, it just oxidized from sitting there a while.

The first beaker will have gold fingers and pieces of plated boards in it. None of these pieces have solder or components on them.

If I have enough solution and leave it there long enough (months), everything should come off of the board right? (I'll be stirring it now and then) The green mask should come off, since the copper underneath will be dissolved also.

It's possible that some of the green mask won't be removed, since I'm not using a bubbler. There isn't any gold plating under the green mask on these boards, so I'm not worried about it that much.

I'll check with stannous to be sure, but there shouldn't be any dissolved gold since I didn't add a bubbler or oxidizer.

After filtering and rinsing, I'd be left with the gold foils and green mask. Dissolve the foils with HCl/Cl and filter. The green mask will be left.

Drop the gold with SMB and re-refine.
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Beaker two will have gold pins. The pins don't have solder or anything else on them.

I'm putting them into a solution of "pre-made" CuCl2, just like the first beaker and letting them sit for a couple weeks or months also.

I'm going to stir the solution once in a while, and filter out the foils when I start seeing a bunch floating around, until the pins look like there isn't any more gold on them.

I shouldn't need to completely dissolve the pins this way, since there isn't any oxidizer.

There should just be foils left and not the black mud from gold cementing out, because the gold isn't getting dissolved. (I'll be checking with stannous to be sure)

Afterwards, I'll dissolve the foils with HCl/Cl, then filter, rinse and drop the gold with SMB and re-refine.



If I wanted to speed this up a lot (and actually work on it for a day or two), I could just do all of this in a crockpot on low/medium with a bubbler, but I've been busy lately.

Edit 2x - spelling

There have to be a source of oxidizer somewhere for copper chloride to work. (Hydrogen peroxide, air, electrolytic oxidation.) If you only leave it without a bubbler the oxygen will have to diffuse from the surface. It will work but fingers in a beaker usually takes from a week or two up to a month or two, depending on how much copper chloride you start with and the amount of fingers, as well as the geometry of your beaker. A wide and shallow setup is faster than a deep, narrow one.

The copper under the solder mask will eventually be dissolved too, but even then the solder mask will probably be strong enough to not break unless you attack it mechanically.

I have run a lot of batches of fingers with just a beaker with HCl and time, removing cleaned fingers and dropping in more as I scrapped more boards.

If you have pins made from a copper alloy or even other metals, some of the copper will cement out onto the pins and if it is too much it will remove all copper and leave you with a chloride solution that doesn't dissolve the copper.
I use old copper chloride solution to remove pins from the last generation of pinned CPU:s, for example P4 CPU:s. The pins are made from kovar and soldered with tin solder. 10-15 minutes in a copper chloride bath removes all the pins and MLCC:s on the board.


Beware, running fingers and pins without a bubbler can be very slow... especially if you do it in the winter. :wink:


Göran

g_axelsson said:

There have to be a source of oxidizer somewhere for copper chloride to work. They'll be in a beaker, open to the air.

The copper under the solder mask will eventually be dissolved too, but even then the solder mask will probably be strong enough to not break unless you attack it mechanically.That's why I wasn't too worried about the solder mask. The pieces I'm working on don't have gold plating under the green mask.

For the boards that do have gold underneath, I'm either using Potassium Hydroxide (Slaked Lime) if it'll will work the same as Sodium Hydroxide. Or I'm just using a wire brush to scrape the mask off and process everything.

I have run a lot of batches of fingers with just a beaker with HCl and time, removing cleaned fingers and dropping in more as I scrapped more boards.That's the same way I always ran fingers

If you have pins made from a copper alloy or even other metals, some of the copper will cement out onto the pins and if it is too much it will remove all copper and leave you with a chloride solution that doesn't dissolve the copper. I noticed that while running a few pounds of pins before. The solution completely turned into Zinc chloride (grey/clear). I kept needing to siphon most of it and add more HCl/H2O2 until it worked properly.

Beware, running fingers and pins without a bubbler can be very slow... especially if you do it in the winter. :wink: I've done this quite a few times also

Click to expand...

I'll just run the fingers and pieces of boards with HCl and time like usual. Seems to be the easiest way.

The pins are magnetic so it would be easier if I just completely dissolve them. I'll use a crockpot on medium/high and a bubbler when I finally get around to it.

Edit - reworded