Just wanting to make sure

[hammerdown]

I have boards of various types where I have mechanically removed/depopulated all the components and all that is left is solder... maybe a few boards where component through-hole pins are still stuck in the holes thanks to the solder, but the components themselves are removed... and I'm getting about ready to start them through recovery processes. What I want to make sure I understand right is... soaking the boards in a warm 50/50 HCL/water cocktail for an hour or two is the usual preferable way to remove the solder, then rinse with warm water, dry, then place in CuCl2 to recover the gold plating and boards with flash plating (like whole board gold coated such as some toughpads & soundblaster cards after a lye bath & light scrub) process in HCL/Cl to recover the gold... correct? Or would just placing the ones that don't have flash plating right into CuCl2 attack the solder without hindering the gold foils/particles?

 

[kurtak]

soaking the boards in a warm 50/50 HCL/water cocktail for an hour or two is the usual preferable way to remove the solder

I don't have the time to post about the entire process you want to do (such a post would be HUGE & take a LOT of time

However - that said - you DO NOT want to dilute the HCl 50/50 (acid/water) to remove the solder - use the HCl full strength (31/32 %) & you don't "need" heat --- as long as it 60 degrees F or higher outside the (full strength) HCl will work just fine - below 60F it will still work just "a bit" slower

Diluting acid 50/50 with (distilled) water is only something we do when using NITRIC acid that is 67 - 70 % for dissolving silver &/or base metals (like copper/brass) with nitric acid

if the nitric you are starting with is less then 67 - 70 % (in other words already diluted) you also don't need to dilute the full 50/50 --- in other words how much you dilute depends on the starting strength of the nitric

Kurt

 

[hammerdown]

I thank you Kurt for replying. I'm not necessarily looking for the whole recovery process in responses, unless I'm just way off the mark in how I'm doing anything. I have been removing soldermasking from full Au coated boards (last picture) via warm Lye & saving the boards until ready to attempt HCL+CL ..and.. I have been recovering foils from clean boards and fingers via CuCl2 and collecting in a large beaker for later refining when I feel ready, both processes for a couple or so years now. I even processed a batch of fingers that weren't cut close that had some solder on the edges last year, filtered out the foils and saving the solution until further knowledge & readiness on how to maybe recover other PM from the solution. But rather than process these current boards I have (1st picture below is an example of some that I have) that are depopulated, but still have solder left behind, like I did those solder containing fingers of last year in CuCl2, I thought I'd finally give it a go at trying solder removal first before gold recovery.

I apologize for my not understanding correctly that diluted HCL won't work for solder removal. I thought I read from many posts here & there that diluted HCL (heat just sped it up a bit) was the best way to 1... avoid digestion of any possible PM's mixed in with any possible unwanted base metals with straight ~31% HCL ...2... saves acid use due not needing the strength of ~31% to just remove solder... and 3... better for beginners. Patients I have, so I'm not necessarily looking to cut any corners... but I also don't want to add extra steps that aren't need or would actually complicate things later or to unnecessarily prolong a process by going too slow. So again, thank you for clarifying for me. I will just straight HCL soak these boards to remove the solder.

As far as any nitric uses, although I did purchase 2.2L of ~70 nitric acid a few years ago on impulse, I don't feel I'm ready for that just yet... but thanks for the tips. I'll add to my notes of nitric.

I do however feel ready to attempt HCL+CL with clean (de-soldered & de-soldermasked) flash-plated material plus printer ink ribbon & flat ribbon wire ends later this Spring or Summer with proper PPE and the outside breeziness of my area. A fumehood just isn't feasible for me at present.

I tried imbedding pictures via a website picture host to help save GRF storage space, but it won't let me post that way claiming it can't determine the picture dimensions of from the link. So below are the pictures added. 1st one is a sample of my boards with solder that I originally posted about... and the other 2 pictures are samples of my material that I think the HCL+CL process is the way to go for recovery.

 

[Shark]

In the first picture, those black epoxy like blobs need to be removed as there is gold under them. Some can be removed simply by flexing the boards and prying them off. Others can be removed by chipping at them with the sharp claw of a hammer and breaking the blob up, even a screw driver will work but may need some help from a hammer.

None of your material will produce much gold unless you have very large quantities. But it is where I started as well, and the experience gained can be worth the effort.

 

[hammerdown]

In the first picture, those black epoxy like blobs need to be removed as there is gold under them. Some can be removed simply by flexing the boards and prying them off. Others can be removed by chipping at them with the sharp claw of a hammer and breaking the blob up, even a screw driver will work but may need some help from a hammer.

I plan on going after the black epoxy blobs after the foils / flashing has been recovered because then, for me, I won't have to worry about board breaking into tiny pieces with gold still on them. I have the worst luck getting those blobs off no matter how I try lol. But I will save them afterwards for eventual pyrolysis processing when ready.

None of your material will produce much gold unless you have very large quantities. But it is where I started as well, and the experience gained can be worth the effort.

The pictures are just samples of my material ready to process at the moment, but I understand what you mean. I'm not having much expectations on yields of any of my material. I have seen vvarious reported yields of this n that material from various sources n people where the yields seem to widely vary. I've just been collecting n storing recovered product (foils so far with some blackish powders) with intentions of finally attempting 1st stage refining later on this year or the next.

 

[hammerdown]

A quick addendum if I may... For boards that are depopulated, but still has solder left behind AND flashing under the solder mask, which procedure would anyone recommend for one without expert experience, but still wants to "go for the gold" + experience despite the minuscule yields?...

Either... ~30% HCL soak to remove the solder BEFORE lye soaking to remove the solder mask...or... HCL soak AFTER lye soaking...or... lye soak with the solder still on the boards and just start the recovery process of choice?

It's my understanding that for boards that are fully plated under the solder mask, that the plating is usually ENIG (flash plating) and therefore would be best to process through HCL+CL method instead of CuCl2 (leach?) since the gold will come off as fine particles instead of solid(ish) foils via the latter... am I correct?

If in case it is suggested to start the recovery with the solder still attached to the boards after lye soaking, how will the varying %'s of tin/lead/silver in the solder, not to mention possible nickel layer between the gold & copper substrate, via HCL+CL method impede my efforts? I think I understand that should I go with the CuCl2 (leach?) method instead, that I may very well have those contaminates in my gold particles to have to contend with, but with HCL+CL, the gold should be in the solution instead of as solids in the bottom... I just haven't gotten far enough, yet, into researching what all metals are affected by HCL+CL and subsequent steps as I think I know with CuCl2. Lord I hope I'm getting this knowledge down somewhat right from my research & note taking lol

 

[kurtak]

HCl/Cl leaching dissolves gold just as AR dissolves gold

BUT - HCl/Cl also dissolves copper just as AR dissolves copper

Therefore - just as putting copper in an AR solution with gold dissolved in it will cement the gold out of the AR - copper in a HCl/Cl solution with gold dissolved in it will cement the gold out of the HCl/Cl

Therefore - whether using AR or HCl/Cl - though gold will dissolve - as long as copper is present - the copper will cement the gold out

In other words - you can not simply dissolve the gold & leave the copper behind --- you have to dissolve both "all" the gold & ALL the copper so the gold stays in solution in order to then precipitate the gold from the solution that has ALL the metal dissolved in it --- other wise much of the gold cemented by the copper is going to be stuck to the copper &/or in the little holes in the boards - it's just no longer going to look like the original gold plating on the boards

Edit to add; - in other words there are no short cuts --- you ether dissolve ALL the metals & then precipitate the gold --- or - remove the base metals first & then refine the gold (foils) after removing the base metal

Kurt

 

[hammerdown]

Thanks Kurt! I actually hadn't learned yet about the other metals being dissolved in HCL+CL. I somewhat thought perhaps copper, but wasn't certain about other metals. So the hierarchy of metals dissolved-to-percipates is virtually the same as via CuCl2.

I apologize if I seem to be seeking shortcuts. I am not necessarily looking for shortcuts for the sake of impatience or whatever, but rather I'm just trying to think ahead of avoiding unnecessary, or even causing bad, added problematic steps.

So what I gathered from your reply is to HCL soak to remove the solder before recovering the gold from ENIG plated boards just as with other boards... yes? But what about the initial question regarding the soldermask? Should I remove the solder before the lye soak or after the lye soak?

 

[hammerdown]

Here is what I have ready thus far of full plated boards (ENIG or otherwise) that is depopulated and awaiting the next step of either solder removal or soldermask removal THEN solder removal. I'm sure it still isn't much, but surely these boards, along with my other already cleaned full plated boards, will be worth starting (attempting) the recovery of the gold this summer once cleaned of solder & soldermask.

Oh... I also have quit removing card fingers from full plated boards to help add to the recovered gold from full plated boards since ENIG results in minute amounts by volume.

 

[hammerdown]

Didn't realize the attachment limit is 5 per post. Here are the rest.

 

[Shark]

Those are the kind of boards I started out with. Basically what ever I found in trash. I would clean the components off and drop them into a five gallon bucket of AP. If I found one , I added one. If I found half a dozen, I added half a dozen. As I added the days find, I would check the old one's and remove the bare board when it was stripped. After a few months or when I got bored, I would process what ever was in the bucket. The longer I waited the more gold I had. This still works when I have them and letting them sit lets me concentrate on other things where necessary, while building up some extra on the side. I kind of miss those day.

 

[hammerdown]

Hey there Shark!

Sadly, this is just a side thing for me. I don't get material often enough to concentrate day in & day out time to. I typically cherry pick personal choice items off of boards and stash away separated for possible future processing, and then sell the non-full plated boards to a local scrap yard that buys them from me as is. For full plated boards, after I cherry pick, I manually remove the remaining components by hand and just keep mostly jumbled up in a container for who knows what later on. I rarely choose to use my air chisel due to my uber greedy power company. For full plated boards that I've cleaned off all components, but still has the solder left behind, I will use my Dremel tool with a small grinding wheel to hit the solder points if there aren't too many points, then after a stash of boards have built up, I will lye soak to remove the solder mask. I just haven't yet gone any farther with those full plated boards after de-masking since I know most will be super thin plated or ENIG coated and probably won't come off as foils. The only other process I have done & become fairly certain that I know what I'm doing (after typical rookie mistakes in the beginning) is the CuCl2 (I hear yay and nay on whether or not to call that AP since the solution has copper in it after starting a fresh batch of HCL+Peroxide) to remove gold foils off of card fingers and other board trimmings. So far, all my foils and whatever powders that has come with it that I have recovered from fingers & trimmings are all being stored in a large covered beaker that I keep adding more foils to as I recover them.

I have heard of others who put whole boards in AP or CuCl2 to remove everything and then sort it all out later. I so don't feel I'd be wise to attempt that just yet. I've also heard of some who put cleaned fingers and boards right into AR, bypassing the AP step, but again... I don't feel ready for that either. Not to mention that I have yet to attempt the use of nitric acid. I do envy guys like you who have experince and confidence of doing more advanced steps, or even side-stepping some steps, that enables you to process faster... but I'm not letting envy & impatience get in my way of learning proper first if I can help it. Gotta crawl before can walk, gotta walk before can run. I've done had some earlier on rookie mistakes on trying to start sooner than I was truely ready on certain things (I stll need to figure out a way to fix 2 certain mistakes from the past too lol), and of course causing a relatively simple AP / CuCl2 leach process to be more hassel than it should be. One can't learn to succeed if they don't first fail some

 

[Shark]

I removed all components from the boards, mainly with a plastic mallet and a wide wood chisel. I did cherry pick certain items first, the rest went in a pile that I would pick through whenever I had a spare bit of time. Once cleaned of all parts, any boards with gold left went into the AP, such as those sound blaster cards. A fair bit of the copper I melted for studying copper cells came from the saturated AP. I would leave the boards in AP long enough to take the solder mask along with all other base metals off. I did this mainly with smaller boards such as the ones you pictured. I also removed the black "knobs" while cherry picking the other items. When ready I would filter out the solution, flakes, solder mask and all, incinerate and run in AR. The main thing was I had time to let them sit until they were fully striped. At the time 100% of anything I could make from the boards and gold went into getting better equipment and material to work with. It took a few years to get to a fairly comfortable level of both, and I still have a wish list for equipment. The cherry picked items I would process later but some choose to sell them because they can be a bit more complicated to do, or they just lack the space to do them comfortably. The main thing is to have a plan you feel capable of, and follow it. Refining is the easy part, recovery can be the real monster in the shadows.

 

[hammerdown]

I may end up trying your way at some point with the set it & forget it, then incineration and so on. Truth be told, I have at times wondered about doing something rather similar, but then figured I was probably thinking too much like "short cut thinking" and then have a bigger problem afterwards that could've been avoided. And perhaps that would be true of my current knowledge, capabilities (no incineration nor pyrolyzing equipment) and comfortability level. I guess my previous blunders have caused me to be more cautious and slow stepping until comfortable before jumping to other processes just because it seems easy lol For instance... one method I've read about and seen that looks tantalizing is the stripping cell for misc plated metal pieces, but after at least 3 years of knowing about it, I just don't think I ready to attempt it just yet. Mainly due to lack of sufficient work area for it, but also the absence of sulfuric acid use experience. Same goes for nitric acid. All in time though. I do have concentrations of both acids from about 3 or 4 years ago from an impulse buy stored away for when I'm ready to play mad scientist.