Solder

[Romix]

Is there a way of removing solder leaving copper untoched?

 

[kurtak]

HCl --- HCl dissolves tin but not copper --- unless an oxidizer is added like H2O2 (peroxide) then the HCl will also dissolve the copper

 

[jason_recliner]

HCl will eventually attack copper too; once it starts absorbing oxygen from the air.

Depending on the physical situation involved, you may be able to use solder's much lower melting temperature to remove the majority, before using HCl to clean up the rest.

 

[Anonymous]

Yes Jason, the key word is "eventually." For the purposes of removing solder it shouldn't be left in HCl for longer than it takes to remove the solder. Some common sense has to be applied in it's application mate.

Jon

 

[Romix]

HCl will eventually attack copper too; once it starts absorbing oxygen from the air.

Depending on the physical situation involved, you may be able to use solder's much lower melting temperature to remove the majority, before using HCl to clean up the rest.

Yes, and copper after contact with HCl, later easily oxidises on air.

 

[kurtak]

HCl will eventually attack copper too; once it starts absorbing oxygen from the air.

Depending on the physical situation involved, you may be able to use solder's much lower melting temperature to remove the majority, before using HCl to clean up the rest.

Yes, and copper after contact with HCl, later easily oxidises on air.

Ok & yes - what are you trying to do? --- clean some copper? --- or just remove the solder before other processing?

Kurt

 

[Romix]

HCl will eventually attack copper too; once it starts absorbing oxygen from the air.

Depending on the physical situation involved, you may be able to use solder's much lower melting temperature to remove the majority, before using HCl to clean up the rest.

Yes, and copper after contact with HCl, later easily oxidises on air.

Ok & yes - what are you trying to do? --- clean some copper? --- or just remove the solder before other processing?

Kurt

second

 

[jason_recliner]

Then HCl sounds like your thing.
If you have great blobs of solder, I'd still remove as much as you can by other means first, such as melting it off.
If it's just a light coating, straight into HCl.

 

[goldsilverpro]

Solder on boards can have several different compositions. If it's mainly tin, an old formula in the plating industry for removing tin without eating the copper is:

HCl (probably tech grade 37%) - 1000ml
Water - 62ml
Antimony trioxide - 15g
Room temp

This leaves a loose adhering smut of antimony on the copper which can be wiped or scrubbed off. The Sb smut tends to protect the Cu.


Of course, just concentrated HCl alone will dissolve tin at room temp. In general, the stronger the HCl, the less attack on the copper. For example, I think muriatic acid (HCl = 31.45%, usually) would be more likely to attack the copper than the stronger 37% technical grade hydrochloric acid.

 

[rickbb]

I depopulate boards with heat first, then soak in Muriatic at room temp for about an hour. Gets all the tin solder off nicely, then go to CuCL2 for copper dissolution to release the gold plate.

 

[Justincase]

I hope you do not mind yet some more silly question's.
Can we see a picture of what you are working on? why do you want to save the copper?do you have a use for the intact board ?
I can not see why people bother trying to process circuit board's them self any way.
There are one or two bit's of low hanging fruit which become interesting to process when you accumulate ten or twenty kilo's.
But 99% of what I am finding is uneconomical to process and must be saved into large loads which can be sent on to a smelting operation.
and as you have to send in large loads any way it makes little sense to spend time on similar material even if it is particularly good looking,I just add it to the crate to sweet the return as the fees stay mostly the same even if they return more metal to you.
Why pay a dog and bark your self.after you add up the cost the equipment and the time it take's some of the larger firm's work out much cheaper than D.I.Y. and have impressive systems for accountancy of the returns.

 

[Grelko]

I hope you do not mind yet some more silly question's.

Since HCL dissolves tin, what happens to the silver in certain types of solder? HCL doesn't really attack silver , so would it just drop to the bottom as powder/flakes, since the tin would be in solution leaving the silver behind?

I figure the silver wouldn't stay on the board because it's mixed in with the tin.

If this would drop silver as flakes/powder, couldn't you reclaim it without the need for nitric etc?

 

[Justincase]

I hope you do not mind yet some more silly question's.

Since HCL dissolves tin, what happens to the silver in certain types of solder? HCL doesn't really attack silver , so would it just drop to the bottom as powder/flakes, since the tin would be in solution leaving the silver behind?

I figure the silver wouldn't stay on the board because it's mixed in with the tin.

If this would drop silver as flakes/powder, couldn't you reclaim it without the need for nitric etc?

I should think the only thing hydrochloric acid would do to modern silver solder would be to form a coat of silver chloride.
And the tin chloride formed when removing tin based solder might cause problems further along the line so great care would have to be used to wash every thing before further processing.And if they had soldered gold plated parts All the very finely divided Au that had been dissolved in the solder would now be in with all the muck.
What a lot of hassle,it would have to be extremely thick gold paste under the solder and a very large board to make it worth while.

 

[Grelko]

I should think the only thing hydrochloric acid would do to modern silver solder would be to form a coat of silver chloride.
And the tin chloride formed when removing tin based solder might cause problems further along the line so great care would have to be used to wash every thing before further processing.And if they had soldered gold plated parts All the very finely divided Au that had been dissolved in the solder would now be in with all the muck.
What a lot of hassle,it would have to be extremely thick gold paste under the solder and a very large board to make it worth while.

I'll have to look into this a bit more. I have close to 100 pounds of industrial boards from the 50-60s but, the solder could be a mix of lead instead of silver though. I haven't checked them yet. Thanks for the info.

 

[Justincase]

I should think the only thing hydrochloric acid would do to modern silver solder would be to form a coat of silver chloride.
And the tin chloride formed when removing tin based solder might cause problems further along the line so great care would have to be used to wash every thing before further processing.And if they had soldered gold plated parts All the very finely divided Au that had been dissolved in the solder would now be in with all the muck.
What a lot of hassle,it would have to be extremely thick gold paste under the solder and a very large board to make it worth while.

I'll have to look into this a bit more. I have close to 100 pounds of industrial boards from the 50-60s but, the solder could be a mix of lead instead of silver though. I haven't checked them yet. Thanks for the info.

It is a pain but you must be strict with your self.unless you are simply experimenting for the fun of it.
I approached twenty five different persons and company's to compare services and rates and was very disappointed.
Started off intending to send out 100K lot's of sorted boards but found most of the small operators actually tried to insist I send out smaller lot's that would have been impractical to value accurately.Not a good sign and about half showed outward signs of aggression when informed they where being given comparative lot's.
So have been forced to keep stock piling so I can take advantage of the better rates offered by a European company.The entry size of lot is 2000K for high return boards like cell phone's or 5000K for standard electronics like mother board's.
Once you get to that level they pay out on most element's and help with the transport cost's.
Still saving though it is quite an easy way to accumulate capital.
Have applied for a W.E.E.E. license on a small storage site so fingers crossed may send off my first load soon if that come's through.

 

[Grelko]

It is a pain but you must be strict with your self.unless you are simply experimenting for the fun of it.

Sorry to derail the thread a bit.

It's basically a hobby that I picked up last year. While collecting scrap metal, sometimes people give me their flat screens, computers, etc, to tear apart, so I've been collecting the boards from everything. I probably have close to 400 pounds ( ~180K) of material so far over the last 10 months or so.

I've been reading and learning all I can from this site along with certain youtube videos, and began slowly processing fingers and pins a few months ago.

Sometimes I'll take a few small pieces to the jewelry shop down the road since they have an XRF to see what they're made of. Once I get enough items that aren't worth processing myself, I'll drive up to boardsort, since they're about an hour away. Also, the scrapyard a couple miles from here, take boards but don't pay much, so I only take brown boards to them.

There is a place the next state over that I could send the materials to, and get metals or a check, but shipping is horrible. If I get around to making/buying a ball mill, there is a place close to me that processes ore/powder, so I could take it to them, or just do it myself.

I've talked to a few companies in the past, but most of them want something like 30% of everything, plus all of the copper, and don't help with shipping unless I had tons of materials.

Besides all of that, this hobby is very fun

Edit - added number in kilos

 

[MarcoP]

Justin, I hope your W.E.E.E. license comes in soon, just yesterday I got my accountant into setting up a small business to refine for jewelers and such, not ewaste though.

Marco