Removing heavy solder on power boards

[Juan-2-many]

Hi Friends
What are some techniques to remove heavy amounts of solder and also when the tiny gold holes have solder in them? My goal is to reveal clean gold for processing. Here are some front/back pictures.

 

[Yggdrasil]

Hi Friends
What are some techniques to remove heavy amounts of solder and also when the tiny gold holes have solder in them? My goal is to reveal clean gold for processing. Here are some front/back pictures.
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HCl will take care of the Solder.

 

[Martijn]

Hi Friends
What are some techniques to remove heavy amounts of solder and also when the tiny gold holes have solder in them? My goal is to reveal clean gold for processing. Here are some front/back pictures.
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You can heat one spot with a soldering iron and when it melts, tap the board on a wooden board or your workbench. That removes most of the solder. You can also loosen the components that way. A fine copper wire on a spot with the soldering iron on it can suck up hard to get spots.
Then go for HCl if you want the board clean.

 

[Juan-2-many]

You can heat one spot with a soldering iron and when it melts, tap the board on a wooden board or your workbench. That removes most of the solder. You can also loosen the components that way. A fine copper wire on a spot with the soldering iron on it can suck up hard to get spots.
Then go for HCl if you want the board clean.

Thanks, I like this idea. HCl is my last resort. There’s a lot of brass and copper on these boards. I’m trying to avoiding damaging the pcb as much as possible because I don’t want my scrap yard downgrading them due to PMs being dissolved and/or corroded.

 

[Martijn]

Make sure your scrapyard grades the boards at a much higher price when cleaned, or you will loose money. Calculate the weight loss of any brass or other heavy metal parts you remove from the low grade boards and the time you spend doing it versus the money you'll get from handing in a bucket full of brass. Will that be worth it in the end? It may be worth it.
That plating could very well be ENIG plating, meaning ultra thin, not high grade. get the number down before you put the time in.

 

[anachronism]

Thanks, I like this idea. HCl is my last resort. There’s a lot of brass and copper on these boards. I’m trying to avoiding damaging the pcb as much as possible because I don’t want my scrap yard downgrading them due to PMs being dissolved and/or corroded.

If you have access (and the safety experience to use it) to NaOH this will both take the tin off and remove some if not all of the solder mask. You need it warm/hot, so eye protection and safety clothing are absolutely essential but it will do a better all round job without the "collateral damage" that HCl causes. One thing to note- remove any Aluminium before you do it because that will go up into solution (as it will with HCl.)

 

[offtrailhiker]

If you have access (and the safety experience to use it) to NaOH this will both take the tin off and remove some if not all of the solder mask. You need it warm/hot, so eye protection and safety clothing are absolutely essential but it will do a better all round job without the "collateral damage" that HCl causes. One thing to note- remove any Aluminium before you do it because that will go up into solution (as it will with HCl.)

There's an old post about that: https://goldrefiningforum.com/threads/ratio-to-mix-up-lye-bath.22224/. It sounds dangerous, though.

 

[Juan-2-many]

There's an old post about that: https://goldrefiningforum.com/threads/ratio-to-mix-up-lye-bath.22224/. It sounds dangerous, though.

woah. Only thing I know about lye is from Fight Club but I can’t talk about it. thanks for linking the thread

 

[Shark]

Lye, along with most chemicals we use is or can be dangerous. It is up to the individual to use them safely and responsibly. Under proper conditions lye can used relatively safe, used recklessly it can burn, maim or even kill. So will about any of the acids we use including vinegar and more.

 

[g_axelsson]

Any gold plate with solder on is dissolved in the solder. If you dissolve the solder in acid or NaOH, you get the gold back as a fine mud. The question is if it's worth it. Often gold plating on solder surfaces are made with ENIG and is just a thin plating so the chemical costs could easily exceed the value of the gold.

Göran

 

[anachronism]

Lye, along with most chemicals we use is or can be dangerous. It is up to the individual to use them safely and responsibly. Under proper conditions lye can used relatively safe, used recklessly it can burn, maim or even kill. So will about any of the acids we use including vinegar and more.

Absolutely right Shark. Almost everything we use is dangerous. I think it was GSP who once commented about risk and mitigation.

 

[Badman]

I won't use Lye to wash solder mask. I can't stand the awful wretched smell of hot water and lye. It makes me go like some guy named Gonzo in these forums (crazy).
HCL, manual scraping, Solder wicks, Drills, epoxy strippers, Nail Polish remover, anything is fine but Lye ? IT'S PUTRID.

The smell of Lye reminds me of a Drunks Vomit & Foot Fungus.

In some Countries maybe Lye is all you can get and cheaply, how Sad or that person is cheap idk

 

[anachronism]

I won't use Lye to wash solder mask. I can't stand the awful wretched smell of hot water and lye. It makes me go like some guy named Gonzo in these forums (crazy).
HCL, manual scraping, Solder wicks, Drills, epoxy strippers, Nail Polish remover, anything is fine but Lye ? IT'S PUTRID.

The smell of Lye reminds me of a Drunks Vomit & Foot Fungus.

In some Countries maybe Lye is all you can get and cheaply, how Sad or that person is cheap idk

Well that's certainly an interesting perspective.

 

[Badman]

Lol, that's just me, no tolerance to lye but your experience may differ. Try some out for yourself and this topic got sidetracked by lye instead of tin solder which is a very removable low melt temperature alloy. If you don't know how to remove solder how are you gonna remove the Gold ?

 

[Yggdrasil]

Lol, that's just me, no tolerance to lye but your experience may differ. Try some out for yourself and this topic got sidetracked by lye instead of tin solder which is a very removable low melt temperature alloy. If you don't know how to remove solder how are you gonna remove the Gold ?

Usually one either heats and remove or dissolve in HCl.
Or a combination.
Lye is another tool in the box.

 

[Martijn]

Lol, that's just me, no tolerance to lye but your experience may differ. Try some out for yourself and this topic got sidetracked by lye instead of tin solder which is a very removable low melt temperature alloy. If you don't know how to remove solder how are you gonna remove the Gold ?

He wants to turn in the cleaned boards for a higher price, basically upgrading the boards. And not harming them with a chemical bath changing their appearance, lowering the price or maybe even rejecting the boards as chemical waste.
If that is profitable in the end for him, is a question only he can answer.
But he is not going for that ultra thin ENIG layer of gold plating, as far as i understood.

 

[Martijn]

My goal is to reveal clean gold for processing.

Any gold plate with solder on is dissolved in the solder. If you dissolve the solder in acid or NaOH, you get the gold back as a fine mud. The question is if it's worth it. Often gold plating on solder surfaces are made with ENIG and is just a thin plating so the chemical costs could easily exceed the value of the gold.

Göran

If you read Goran's post, there is no reason to reveal ENIG plating under solder. Molten solder is a solvent for precious metals. The gold will be in the solder, not on the board. So if that's your goal, forget it. There will be no gold revealed, it will be in the solder.
another point is that any experienced scrapyard will recognize ENIG. looks great, but not much there.
Removing aluminum, brass, plastic does raise the boards value, but also lowers the weight.... if removing solder pads raises the value, I'm not sure.

 

[andu]

If you want to get rid of tin alone there's some vids on youtube, but can't remember how they actually worked, keeping the boards untouched sounds a bit hard, however, there's quite a few combinations out there you could try for stripping tin.
I can't find any of the original videos I had in mind, I however stumbled upon this https://goldrefiningforum.com/threads/remove-strip-only-tin-from-pcb-traces.29454/ .

 

[offtrailhiker]

If you read Goran's post, there is no reason to reveal ENIG plating under solder. Molten solder is a solvent for precious metals. The gold will be in the solder, not on the board. So if that's your goal, forget it. There will be no gold revealed, it will be in the solder.
another point is that any experienced scrapyard will recognize ENIG. looks great, but not much there.
Removing aluminum, brass, plastic does raise the boards value, but also lowers the weight.... if removing solder pads raises the value, I'm not sure.

In my experience removing extraneous material will raise the value of the board. And for low-grade boards, the copper and brass is worth more than the board.

 

[Ag and Au]

I have had reasonable success using this method:
1) Depopulate the gold-plated PCBs with an electric chisel (it is not worth the time for ENIG plated boards).
2) Heat the "component side" (not the remaining stubby-lead side) outdoors with the propane heater.
3) Quickly hit the board with compressed air. The lead stubbs blow right out the rear of the board.
4) Clean up any remaining solder splash with solder wick and a solder iron.

Advantages:
A) Very little fumes
B) No chemicals
C) Very inexpensive

Hope this helps.