transistors in HCl

[kole55]

hello everyone. I have about 400 grams of transistors with 3 legs. I removed the caps mechanically. Only the lower gold-plated part remained, which I boiled in HCl outdoors. When it cooled down, I filtered and separated the flakes. Normally, maybe I dissolved 40% with one boiling material. I used 1 liter of hcl, gradually adding it. I added hcl to the rest and it works, and I plan to do it cold, I'm not in a hurry. Now I'm interested in why the solution has such a disgusting smell and what kind of reaction is happening. what evaporates even when cold, it has a disgusting smell stench, copper chloride has no such stench at all. thanks for every answer.just to add, last year with the same thing I had about 300 grams of transistors and I put them together with the needles in copper chloride and they dissolved but I also smelled that disgusting smell. Now I decided to do it separately so as not to contaminate the CuCl.

 

[Martijn]

Ive noticed Iron and stainless steel in solution stinks bad. I think it's from metals being oxidized.
A good reminder it is toxic waste.

 

[Yggdrasil]

Ive noticed Iron and stainless steel in solution stinks bad. I think it's from metals being oxidized.
A good reminder it is toxic waste.

Well the Ni and Cr parts in Stainless will definitely be bad,
but Iron Hydroxides should not be much worse than any other
rusted Iron scrap.
Smells are notoriously hard to describe with text and what is bad for one, might be ok for others.

Biology might be behind some of it, because of implication and similarity
to our blood which contains significant
amounts of Iron compounds.

 

[orvi]

hello everyone. I have about 400 grams of transistors with 3 legs. I removed the caps mechanically. Only the lower gold-plated part remained, which I boiled in HCl outdoors. When it cooled down, I filtered and separated the flakes. Normally, maybe I dissolved 40% with one boiling material. I used 1 liter of hcl, gradually adding it. I added hcl to the rest and it works, and I plan to do it cold, I'm not in a hurry. Now I'm interested in why the solution has such a disgusting smell and what kind of reaction is happening. what evaporates even when cold, it has a disgusting smell stench, copper chloride has no such stench at all. thanks for every answer.just to add, last year with the same thing I had about 300 grams of transistors and I put them together with the needles in copper chloride and they dissolved but I also smelled that disgusting smell. Now I decided to do it separately so as not to contaminate the CuCl.

Depending on what is the composition of the base alloy, it may take ages to dissolve at room temperature. Nickel alone dissolves in HCL well if it is at least 60-70 °C, best near boiling point. But kovar like alloys and high chromium steels are PITA to dissolve in HCL, even hot. Fact that you were able to do it hot is good, so it may work even at room temp. There was a thread where one member posted photos of his AP transistor leach - he was going with them for at least couple of weeks.

One more thing to note. Transistors which I processed were heavily plated on the inside. Bulk material was around 8+g/kg gold, so if you cut the hats, you are well over 10-12g/kg. This means plating is very thick and many times acid cannot easily penetrate through cracks in plating. With AR it isn´t an issue, with HCL or AP, it is a big issue and slowing factor.

I do transistors in straight AR precisely due to this. It took ages and I really don´t want to boil the acid for prolonged periods of time If one is using 31% HCL and start to boil, you essentially lose 1/4 to 1/3 of the HCL by evaporation - azeotrope is around 20% HCL. Everything over this number is steadily lost, if the reaction isn´t quicker than boiling loss Altough, from 25% and below HCL concentration, it is relatively OK. Due to this I like AR more - you can steadily hold AR at 60-70 °C, so the evaporation loss is minimal, and you can very well spend 1/3 of the HCL before you reach high enough temperatures to lose HCL significantly.

Of course, nitric isn´t for free but it is a price I want to pay for quicker processing.

 

[kole55]

Depending on what is the composition of the base alloy, it may take ages to dissolve at room temperature. Nickel alone dissolves in HCL well if it is at least 60-70 °C, best near boiling point. But kovar like alloys and high chromium steels are PITA to dissolve in HCL, even hot. Fact that you were able to do it hot is good, so it may work even at room temp. There was a thread where one member posted photos of his AP transistor leach - he was going with them for at least couple of weeks.

One more thing to note. Transistors which I processed were heavily plated on the inside. Bulk material was around 8+g/kg gold, so if you cut the hats, you are well over 10-12g/kg. This means plating is very thick and many times acid cannot easily penetrate through cracks in plating. With AR it isn´t an issue, with HCL or AP, it is a big issue and slowing factor.

I do transistors in straight AR precisely due to this. It took ages and I really don´t want to boil the acid for prolonged periods of time If one is using 31% HCL and start to boil, you essentially lose 1/4 to 1/3 of the HCL by evaporation - azeotrope is around 20% HCL. Everything over this number is steadily lost, if the reaction isn´t quicker than boiling loss Altough, from 25% and below HCL concentration, it is relatively OK. Due to this I like AR more - you can steadily hold AR at 60-70 °C, so the evaporation loss is minimal, and you can very well spend 1/3 of the HCL before you reach high enough temperatures to lose HCL significantly.

Of course, nitric isn´t for free but it is a price I want to pay for quicker processing.

thanks for the detailed answer. I can't work with nitrogen because of the settlement, I prefer AP and hcl+bleach. I did this cooking in hcl far in nature outside the settlement. now I do what's left cold. ok, I always use 16-20% HCL processes and it works perfectly. I think the transistors are of the worst quality, there is no thick plating. Also, after adding 500 ml of hcl to the cold, and two days later, I filtered it again and collected the flakes. Then I rinsed well with water and several times with hot water and shook it in container, took the tweezers and separated the iron rings that came off, the gilding fell from them. All that remained was the middle of the transistor with plastic and gilding that did not fall off. It took me 3 hours to remove the iron rings, but I will save a lot of time and save acid .the transistors are with a weak coating, but I collected a lot of flakes and did one batch of hcl-bleach and got 3 grams. I only have to collect what's left on the plastic, but I'm not in a rush, let it work cold without heating. Thanks again on answer.

 

[Alondro]

Depending on what is the composition of the base alloy, it may take ages to dissolve at room temperature. Nickel alone dissolves in HCL well if it is at least 60-70 °C, best near boiling point. But kovar like alloys and high chromium steels are PITA to dissolve in HCL, even hot. Fact that you were able to do it hot is good, so it may work even at room temp. There was a thread where one member posted photos of his AP transistor leach - he was going with them for at least couple of weeks.

One more thing to note. Transistors which I processed were heavily plated on the inside. Bulk material was around 8+g/kg gold, so if you cut the hats, you are well over 10-12g/kg. This means plating is very thick and many times acid cannot easily penetrate through cracks in plating. With AR it isn´t an issue, with HCL or AP, it is a big issue and slowing factor.

I do transistors in straight AR precisely due to this. It took ages and I really don´t want to boil the acid for prolonged periods of time If one is using 31% HCL and start to boil, you essentially lose 1/4 to 1/3 of the HCL by evaporation - azeotrope is around 20% HCL. Everything over this number is steadily lost, if the reaction isn´t quicker than boiling loss Altough, from 25% and below HCL concentration, it is relatively OK. Due to this I like AR more - you can steadily hold AR at 60-70 °C, so the evaporation loss is minimal, and you can very well spend 1/3 of the HCL before you reach high enough temperatures to lose HCL significantly.

Of course, nitric isn´t for free but it is a price I want to pay for quicker processing.

I've noticed an interesting phenomenon in several of my test tube experiments. For combinations of parts, including kovar, in conc. HCl alone, for about a week nothing much would happen. Then the solution would begin to turn green. After another week, the parts all suddenly dissolved in about a day, leaving only PM plating materials behind, along with some insoluble chloride salts.

What could be happening that almost miraculously dissolves kovar and steel away from such simple starting material? If I could figure out the chemistry involved, it could uncover an easy way to remove some of the more annoying common base metals.

 

[kole55]

I've noticed an interesting phenomenon in several of my test tube experiments. For combinations of parts, including kovar, in conc. HCl alone, for about a week nothing much would happen. Then the solution would begin to turn green. After another week, the parts all suddenly dissolved in about a day, leaving only PM plating materials behind, along with some insoluble chloride salts.

What could be happening that almost miraculously dissolves kovar and steel away from such simple starting material? If I could figure out the chemistry involved, it could uncover an easy way to remove some of the more annoying common base metals.

greetings. It's hard to comment, but at first it seems that the acids don't work, but they work all the time. Maybe you can try to understand from my example. I put 850 grams of cleaned watch cases in AP au, au5, au10, au12,5 and I had a few au20 microns they are all Russian with markings. nothing happened for a long time, I was still using the aquarium pump, then I came up with the idea to wash them with water and cut them into quarters. I had put them whole in the AP. When I started to cut them, I noticed that they were SOFT like margarine and they were in a piece. haha it seems that these weaker acids first prepare the material for the final calculation like boxers. I have a bucket with 4 liters of solution and now I can filter and separate the flakes every day. and every day there is always a certain part of golden flakes. I'm not a chemist, although I graduated from a chemical technical school. I thought a lot about why in every video on YouTube, when the material is dissolved with HNO3, whole needles and clocks remain, while in AP we only get flakes. It seems that nitric acid does not dissolve the nickel barrier between the plating and the base material, so that nickel holds the gilding in the piece. AP breaks everything except the gilding. maybe I'm right, maybe not. it also helps that the gold chloride after treatment with AR is almost always greenish in color. my flakes from AP are very clean even when I work hcl +bleach I have too much golden yellow color from gold chloride. AP is slower but ideal for hobbyists and those who have time.

 

[Yggdrasil]

greetings. It's hard to comment, but at first it seems that the acids don't work, but they work all the time. Maybe you can try to understand from my example. I put 850 grams of cleaned watch cases in AP au, au5, au10, au12,5 and I had a few au20 microns they are all Russian with markings. nothing happened for a long time, I was still using the aquarium pump, then I came up with the idea to wash them with water and cut them into quarters. I had put them whole in the AP. When I started to cut them, I noticed that they were SOFT like margarine and they were in a piece. haha it seems that these weaker acids first prepare the material for the final calculation like boxers. I have a bucket with 4 liters of solution and now I can filter and separate the flakes every day. and every day there is always a certain part of golden flakes. I'm not a chemist, although I graduated from a chemical technical school. I thought a lot about why in every video on YouTube, when the material is dissolved with HNO3, whole needles and clocks remain, while in AP we only get flakes. It seems that nitric acid does not dissolve the nickel barrier between the plating and the base material, so that nickel holds the gilding in the piece. AP breaks everything except the gilding. maybe I'm right, maybe not. it also helps that the gold chloride after treatment with AR is almost always greenish in color. my flakes from AP are very clean even when I work hcl +bleach I have too much golden yellow color from gold chloride. AP is slower but ideal for hobbyists and those who have time.

Acids work on the surface of materials, every surface, it might pick up some Copper from the Gold alloy,
but the main function is that it reduces the "size" of base metal items as they are dissolved.

So after some time one can take it out and maybe be able to remove the Gold from the base metal whole.
Gold is soft already so it will easily be deformed and can slip off.
If you are lucky, it will come completely off, if not, more base metal needs dissolving, maybe after some sorting and cutting.

 

[orvi]

I've noticed an interesting phenomenon in several of my test tube experiments. For combinations of parts, including kovar, in conc. HCl alone, for about a week nothing much would happen. Then the solution would begin to turn green. After another week, the parts all suddenly dissolved in about a day, leaving only PM plating materials behind, along with some insoluble chloride salts.

What could be happening that almost miraculously dissolves kovar and steel away from such simple starting material? If I could figure out the chemistry involved, it could uncover an easy way to remove some of the more annoying common base metals.

Even very simple looking reactions like dissolution of things in AP are indeed very complex processes. Redox potentials can vary widely with concentrations of metal ions and their chlorocomplexes. Some of these reactions are autocatalytic, meaning higher the concentration of one product gets, quicker the reaction proceeds. This is in part also the case with AP dissolution of copper, as copper in solution is effective redox catalyst which takes up oxygen from the bubbles you put through and deliver it to the place. Meaning, no copper in solution, very slow reaction. You can have similar behavior from iron, as two oxidation states (2 and 3) can act as redox pair in some circumstances. But energy barrier is much higher than in case of copper.

I experienced similar phenomenons while dealing with many reactions. Like, sudden reaction of SMB in spent AR solutions... This system is indeed very mysterious to me still to this day. As in some cases, you can have nitric and complexed nitric residues together with dissolved SO2 in solution no problem, and few minutes later it will nearly explode out of the container

I beware of these reactions as much as I can. I, as professional chemist, seek reproducible and tame reactions, predictable and always working. As I see erratic behaviour of the reaction, uncontrollable runaway tendencies, irreplicable results arising from the slightest variation of the inputs, I just abandon it, if there are alternatives with better predictability.

You don´t want to spend time resolving problems, mysterious precipitates and incomplete transformations. Not me. My time is very valuable, so I don´t waste it with these things. Researching reactions and testing is completely different toppic and I did this a lot. But as I once know the reaction isn´t always reliable, I always opt to use alternative, if there is any.

 

[kole55]

Even very simple looking reactions like dissolution of things in AP are indeed very complex processes. Redox potentials can vary widely with concentrations of metal ions and their chlorocomplexes. Some of these reactions are autocatalytic, meaning higher the concentration of one product gets, quicker the reaction proceeds. This is in part also the case with AP dissolution of copper, as copper in solution is effective redox catalyst which takes up oxygen from the bubbles you put through and deliver it to the place. Meaning, no copper in solution, very slow reaction. You can have similar behavior from iron, as two oxidation states (2 and 3) can act as redox pair in some circumstances. But energy barrier is much higher than in case of copper.

I experienced similar phenomenons while dealing with many reactions. Like, sudden reaction of SMB in spent AR solutions... This system is indeed very mysterious to me still to this day. As in some cases, you can have nitric and complexed nitric residues together with dissolved SO2 in solution no problem, and few minutes later it will nearly explode out of the container

I beware of these reactions as much as I can. I, as professional chemist, seek reproducible and tame reactions, predictable and always working. As I see erratic behaviour of the reaction, uncontrollable runaway tendencies, irreplicable results arising from the slightest variation of the inputs, I just abandon it, if there are alternatives with better predictability.

You don´t want to spend time resolving problems, mysterious precipitates and incomplete transformations. Not me. My time is very valuable, so I don´t waste it with these things. Researching reactions and testing is completely different toppic and I did this a lot. But as I once know the reaction isn´t always reliable, I always opt to use alternative, if there is any.

yes you are absolutely right. I can't comment on nitrogen because I decided only on AP. yes you are right because for me AP is quite predictable, for example if there are metal needles I will always have brown copper or metallic copper deposits. This also works in the collection container with the flakes, where I also add fresh hcl, which further cleans the remaining copper and the flakes remain fairly clean. When all the metal material dissolves in the main bucket, CuCl begins to precipitate without metallic copper, and this is a sign that I have no more metal material. Of course, I occasionally refresh the AP with hcl. Basically, I cut the solution in half, remove the saturated solution into another bucket, where I reduce pure copper with an iron bar, and add fresh HCl to the bucket with the material. I do this all the time in a circle, add new material, filter, collect flakes, refresh the AP, and that's always a predictable reaction for me. I also break the processors and insert them into the AP, only the ceramic remains clean later. otherwise, I filter using cotton wool with three funnels and for a long time I do not remove the cotton wool from the funnel, but wash it with a sprinkler into the snowflake collector. When I collect 2-3 grams of snowflakes, I go to hcl + bleach. This is predictable for me and works great.Otherwise, the cotton wool turned out to be better than the coffee filter. First, I don't change it constantly, but wash it with a sprayer. And secondly, what is even more important, it keeps the smallest, microscopic particles of gold on it, all you have to do is carefully rinse it from the funnel with the sprayer into the collector. not too much so that it does not spray from the funnel.