eWaste Mining: Solder Mask Stripping To Reveal Gold 

Sweet! I will be doing some fingers here in a little bit. Check out my video coming up on Monday next week :). Thanks for watching

That is awesome! Be safe. Lye is no joke. Don't let it dry out while you are working with it. Try to prevent splashes or spraying the lye rich solution. This really is nasty stuff.

Thank you for the tip!

Is “goof off” an auto correct? I know of “goo gone” but not goof off. I will have to look. Lye is pretty harsh stuff. It would be fun to try other solutions.

Hey thanks! Been a great year. Nice work to you getting up to about 100.

Hey thanks :)

That is a slick trick :) thanks!

:) sure thing! Thanks for checking out the video!

First: thank you so much for your comments! It means a lot to me. Second: about the toaster oven. It does work really well with surface stuff. The pins that go through the board are really annoying. I find it can work with the toaster oven, but by the time enough solder has dripped away, the circuit board starts to ooze out black goo, and the plastics around many pins have started becoming a misshaped mess that makes working with the pins near impossible. So ... I started doing some research, which lead to some trial and error testing ... and I have found a really nice alternative. Get a cheap paint scraper. Maybe get 2 ... you can use the really flimsly and flexible ones to pop off IC Chips and surface mount things you want. I was always worried about things flying off and getting lost on the ground. That does happen, so work inside a cardboard box. The second scraper should be a nice ridged scraper. One where the blade does not flex. This will sheer off the pins that go through the board. I am actually impressed with how well it works. I break the plastic handle of the scrapers the first day I start with a new tool. But I electrical tape the plastic handle after it breaks, and I still use all 3 of the ones I have ever used since coming to this conclusion. Really, I have not used my toaster oven in 2023 ... and here we are in August. The ultra small things like SMD resistors and the smallest MLCCs are not very good for this process. I would recommend heat for those if you are chasing them ... I stopped since they mix in with the solder too much by the time I am done. I will have to do a video on this very soon. I had someone else ask this same question in the last few days on a different video. Third: Lye ... I have not had any spill on me yet. You are correct, I should be more careful. I can't believe people used to make soap out of this stuff. Very good safety tip. I appreciate the recommendation. Finally, Forth: Klean Strip? I will look into it... how often are boards worth pulling off the solder mask? I only go after boards that look interesting. Since most boards are pretty routine, I have only done it 3 or 4 times in the last year. Mostly, the return is pretty lame on the gold flashing. Sound blaster live cards, laptop track pads, and some older server boards have been interesting. But for the most part, lye has not splashed due to lack of use on my part. Very good recommendations !!! Thank you :).

@@badideametals Thanks for such a thoughtful reply! Awesome to find another prospector. I accidentally learned earlier this evening that Muriatic acid is an excellent way to remove the through hole items. I have a stack of really nice old tektronix boards that have HEAVY gold traces, but in order to use the AP method of recovering those traces and fingers, one needs to depopulate and also get rid of the tin based solder. I removed the mask, which in this case was really a thick polyurethane conformation coating, as that costing locked in both my gold from the traces and the chips that I wanted, many of them with thickly gold plated legs. Once I got all of the masking off, I laid the boards into a small Rubbermaid container... the same one I use for AP leaching, but I just covered them with about a half inch of muriatic acid. I came back an hour later, and all of the tin had settled to the bottom in the little black granules you've probably seen, but to my astonishment, I was able to lift the components straight out of the holes, which has been cleared of solder by the muriatic. You're right about most modern boards, but if you get your hands on any old tektronix or teradyne boards, as well as anything from general aviation radios or old HP Agilent cards, the heavy gold on the traces is easily worth the effort of stripping the mask. I've currently got a stack of tektronix and teradyne going in AP from the late 60's and early 70's and I expect to get suite a yield from just the traces.... Nevermind the pins that came from them. I'm talking thick playing, end to end, and not magnetic. I'll be stripping them in the sulfuric cell. Thanks again for responding. I don't tinker much with anything new enough to have smd types of components, but I've got to tell you - the hour long muriatic acid bath is amazing for gutting the solder and making the components fall out. Happy refining!

This stuff is addictive to me but small scale you have to be pretty determined because this can get expensive to do

The gold is enig plating.

Ya, I say that backwards a few times in different videos. Good catch. :)

Think A-B Acid low Next Base high

Hey thanks! I'll check out your videos when you post too :) ... I am not a pro when it comes to the chemistry. But this is a pretty fun hobby. Just be careful with the chemicals. Some are trying to kill you from the second you open the bottles.

@@badideametals yeah the chemicals scare me, im electrical trade qualified (elec fitter/armature winder, 'A' grade electrician but disabled (cos l was stupid) scrapping fits me, gold recovery fascinates me, keep doing what you're doing l love watching it

Thanks :)

Baking soda won’t do it. Lye is the only way I have seen this work. Admittedly, my knowledge and experience is limited in this area, but if a safer and cheaper solution such as baking soda could have worked, I would imagine everyone would be using it. Sorry. I which it would work :)

:) Thank you so much! I do a few random things, but if you ever want to see specifics, let me know. I have a network board I have a feeling has more gold under the mask ... I will be doing a few "look under the mask" videos here soon before it starts getting cold. I think it is always interesting to see what is hidden.

@@badideametals You are most welcome brother! I have just recently started gold and silver refining and I'm sure I will be watching a lot of your video's and hitting you up for a little knowledge. I just recently poured my first thee 9's fine 1 ounce gold bar from gold filled and karat gold material and got my first silver cell ready for use. I've been prospecting, and recovering gold for years. I love everything gold and silver! So I decided to give the ewaste methods a shot. I am for sure going to be using your method to strip boards. Really cool stuff! Thank you!

Good recommendation :) thanks for checking out the video

@@badideametals Also on a side note on Pyrex and pyrex. Pyrex old school with the capital P is Borosilicate glass just like the lab but if you notice the new stuff without the capital P or maybe it was all caps, it isn't suppose to be subjected to extreme heating conditions its just a measuring cup now as with a lot of their other glassware. Even most anchor products now you have to read their usage label. Most people now a days are buying beakers with handles because I believe if you can't safely use a glass measuring cup in the microwave it's useless ! Useful vid btw ty :)

@@oldkid5212 thanks :) I have a friend who helped me get started with the chemistry stuff. He warned that not all beaker and lab companies are equal. It is sad pyrex is no longer Pyrex… what I keep wanting is one of those old casserole pans that Streetips uses as a catch pan under his beakers… I can’t find any that say they are stove top friendly… I feel it is true, “they don’t make um like they used to.”

:) I have learned so much since this video. I have also acquired better tools and equipment in general. I do appreciate the insights. I have a new solder mask video coming up in the next month or two.

My first thought is that you can use "warm" HCl ... I would not get it too hot... reactions can get out of hand if hot acid is used. Tin dissolves quicker then copper in HCl, and if the reaction is done in warm acid, it will pull the tin into solution pretty quickly. The longer you leave the boards in the acid, the more CuCl you will make (Copper Chloride) which pulls copper into solution faster. I would give that a try. Maybe soak the boards for an hour in warm HCl and see if the solder comes up enough without hurting the copper. You may lose a little silver as the solder goes into solution. You should be able to recover that pretty easy from the SnCl (stannous chloride) made from your soak ... It usually takes a full day of soaking for the copper to start dissolving. Let me know if that works for your application. As always, be careful. I am not a pro, just a hobbyist ... I do this because it is fun. I make a little money because I am getting better at it day by day. Above all, have proper ventilation, personal protective gear, and a way to step away if the reaction makes your environment toxic. Never use heat without knowing what the reaction does cold. Reactions make their own heat as they transition from one solution and compound group to another. Don't rush, or hurry a process. Science and nature have their own rules ... and we are just guests in that space. In short: be safe (and smart) :)

It turned out to be mostly coated by a thin layer of gold flashing... it ended up being mostly copper, but the gold was there on top. It was too light to process by itself. I will be adding it to a future gold refinement run that I will do off camera. Not a lot there... to get a good idea of the gold content, I need to do maybe 50 pounds of boards... which will take time.

Go check out old HP boards, gold everywhere

Do you use lye or something else?

@@badideametals lye!

hmm ... I am not sure why it would take the flashing off. But lye can strip some pretty crazy stuff.

Ya, I got nearly nothing from them.

@@badideametalsyou never will. Ssds write data from one file to several different cells all across the chips. These cells are wiped just meaning they move old data around or to extra space all manufacturers add to ssds. You can't physically use it because it's blocked off but it is necessary for ssds because that's how they operate, constantly moving data around, clearing or wiping cells. Cells begin to degrade BUT depending on the user and how much workload they have meaning storage usage per day etc the faster the cells degrade. Cheaper ssds can be 2 years once again depending on user, high end can be 5 years. Newer technology inside of cells is helping with this, one that intel created cells inside of cells to curb this wiping an entire cell, they explain it like this The advantage of 3D XPoint over NAND is mainly based on addressing (for read and write operations) of single cells instead of whole blocks, where, in order to perform a write operation, a whole sequence of read-modify-write operations has to be performed ( ie clearing cells and writing data else where before the new data is written. By only having to do this to say 1/100 of the cell makes the speed and latency much faster

When I use heat, I get the best results between 350ºF and 450ºF. The toaster oven is not very consistent, and fluctuates between 350 and 450 ... I leave it in until I hear things falling off. If I leave it in too long, the boards start to burn giving off nasty toxic fumes and the boards themselves start to leak out this sticky black plastic that coats everything. Once that happens, it is hard to do recovery on pins and fingers that are coated. So I would say the ideal is 350ºF for about 10 minutes at first. As the oven heats up, that time can go down. Also, some boards have thinner solder beads then others and could be done faster. Something to note! Capacitors are sealed and under heat, they build up internal pressure. They will explode at about 400ºF if they sit for a while. I would wear eye protection. They fly everywhere... there is a ribbon or coil of materials that like to go flying. So just protect yourself. Even after you have it out of the heat, they can erupt unpredictably. Hope that gets you started with heat removal... however, I find gold pin processing to be less efficient and much more time consuming then fingers and ic chips. I am no longer collecting the depoped contents. I have someone who will process the boards further ... I just collect black ic chips, gold cornered BGAs, and card fingers. That alone keeps me busy enough, and I can sell the rest.

@@badideametals thanks I bought a toaster oven and melted components I’ll try at those temps, like you I have boxes of part populated boards, I was looking for an easy way to recover pins as we don’t have a board buyer in Tasmania. Give it another go, I was contemplating building a shred machine and shaker table for fun, then recover through electroplating the copper out. Just need to find scraps and maybe I’ll still make a small scale for fun, thanks

Lye is Sodium Hydroxide (NaOH), and Caustic soda is Sodium Carbonate (Na2CO3). Both are strong alkalis and will make basic solutions when dissolved in water. Lye is a much stronger base than caustic soda unit for unit.

Thank you Andrew for commenting on this post too ... I should make a spot for you to cameo on the channel and help answer these questions.

Sodium Hydroxide can cause major irritations which lead to nausea and vomiting, and even necrosis or dying tissues which can be very serious if not treated. When sodium hydroxide turns into a vapor due to boiling, the lye compounds are transported with the evaporating water in the form of steam. It can get in your eyes and burn. But worse yet, it can get in your lungs and do nasty damage. In short, be aware of where and how you are working with Lye. Know how to protect yourself. Masks and eye protections are recommended.

I am very sorry, and I feel your pain. I have done that too. So frustrating. I have given up on sulfuric (wet) ashing for that reason. It takes a longer time then I liked, and it left me with a nasty smelling mess that usually ended up putting holes in my clothing. Fire ashing, although time consuming, is far cleaner on the waste byproducts then wet ashing is. I have a good deal of BGAs to run ... maybe that will be my next video after the one I am about to publish. Look for it soon ... (I hope) And best of luck ashing. Making "piranha" solution could solve some of your problem, but it also adds more danger to your equation. I don't want to be the one to teach a bad idea, so I leave it up to you to research the safe way to use it. I almost blew up a container of hot sulfuric with it ... I was probably luckier then I know. It was the last time I did it ... the risk did not seem to be worth it to me. Fire is my way now. If you have a forge, that is a good way to do it... if not, a fire ring works too. It takes time, but hey, there are no "get rich quick" schemes that have ever been fast that I have seen. Gold recovery from eWaste seems to be a "get rich by the time you are old" scheme ... and you have to be patient.

The ribbon cables can have gold plated fingers and connectors. Not all do, but most will be thinly and lightly plated.

That would be interesting to try.

Also you might want to use a stainless steel pan to remove the mask. Lye can and does eat glass at high concentrations

Ooo!! Good to know :) I had never tried the mask removal before, so all advice is news to me. Keep it coming! Thanks!

:) I should have asked you before I posted ... But it makes sense... I flipped my PH table in my head.

@@badideametals That's alright, it happens to the best of us. It is kind of confusing and amazing that at either end of the pH scale ~0 and ~14 we encounter solutions that are each very corrosive and dangerous for opposite reasons. Isn't Chemistry fun?

Lye removes a lot :) I use HCl to remove the solder most of the time. They are both really cheap. Thanks for the helpful comment :). I have not intentionally removed solder with lye. How do you do it?

@@badideametals never have done it just seen a guy do it on RU-vid i think he might have mixed it stronger

Hmm, I wonder if he is taking off any precious metals while stripping solder. One of the reasons I like HCl is that it will pull the tin / solder off and leave the base metals such as gold in some instances. If I leave the HCl for long enough, it will also eat the copper and form copper chloride. Once this gets filtered, I will be left with cleaner gold foils (especially while working with RAM and Video cards). HCl is still an acid and needs to be handled properly, and it should not just be dumped without treatment... but it makes my work so easy while working with circuits. I just can't imagine Lye being easier or faster. But I am not a pro at any of this. I am still learning. Feel free to link the lye video if you wish. I am interested to see what that process is. I will not likely switch as I like how I have everything setup right now. But hey, it is always good to understand what is going on and what alternate processes are.