Sorry but that just is not true --- the leads - which are the wires that come off the CB & then go "into" the IC chip will be ether kovar or copper (kovar being the most common) are nickel plated - there is NO reason to plate them with silver
if you are talking about the bonding wires that make the connection between the "leads" & the silicon chip again they are NOT silver - they are ether gold bonding wires or they are aluminum bonding wire - in other words - if they are silver in color then they are aluminum NOT silver
Again - just not true - at least as far as I have seen & I used to process 500 to 600 pounds of IC chips per year (talking about the black epoxy type chips)
if you are talking about ceramic chips that is a different story - which are a completely different process then black epoxy chips
If you are talking about using sulfuric to "carbonize" the epoxy - then you are talking about a process called "wet ashing" which is an EXTREMELY dangerous process & VERY inefficient way to carbonize chips
It's a process used only by You Tube IDIOTS !!! --- & is STRONGLY advised against here on this forum
If you are going to ash (&/or carbonize) epoxy IC chips you are FAR BETTER served doing so by pyrolyzing/incineration --- which is discussed EXTENSIVELY here on this forum
If you are talking about using sulfuric to deal with base metals that a different story --- however - IMO there are better ways to deal with base metals the sulfuric
again sorry but just not true - HCl alone will not react with silver (unless it is VERY finely divided plus heat - plating is not finely divided enough for HCl to react) there needs to be an oxidizer present to react with the silver in which case then (once the silver has been oxidized) the HCl will cause the creation of AgCl
Again just not true - nitric dissolves bismuth - though yes - raising the Ph above 0 (over diluting) will cause bismuth pentahydrate to precipitate
Let me put it this way - after processing several hundred pound of chips per year & literally several tons over the years - bismuth - as a result of treating the ash with nitric has NEVER been a problem that created "a mess"
As I said before - the vast majority of leads are plated with nickel not tin
you are talking about BGA type chips here - & yes if you put them in nitric the nitric will cause the tin solder balls to form the white goo called meta stannic acid - which yes will create a BIG mess - with is why (with this type chip) we first advise to treat with HCl to get rid of the tin --- in other words get rid of the tin before pyrolyzing/incineration
Again just not true - nitric (unless VERY dilute) does not react with aluminum - certainly not in a way that will cause a mess
Nitric acid - when applied to aluminum causes an aluminum "oxide" to form - a "few" atoms thick - on the surface of the aluminum- this oxide - on the surface - then causes the aluminum to "passivate" thereby preventing the nitric from further reacting with the aluminum
As I said - yes - if tin (likely from solder) is involved - nitric will cause the problem of meta stannic acid - which as I also said is why treating with HCl "first" is suggested to get rid of the tin
VERY rarely (if ever) is platinum found in electronic scrap
yes silver & palladium is found in SOME capacitors - but nitric will not separate them as nitric will dissolve both silver & palladium
but never in chips - at least not in the black epoxy chips - ceramic chips are a different story
that depends on your source &/or amount you are buying
When I was full time refining I bought 53% nitric in 55 gallon drums for around $3 per gallon & 67% nitric in 15 gallon kegs for around $7 -$8 per gallon
LOL - sulfuric acid is BY FAR more dangerous then nitric
Not saying nitric is without danger - but lets be real here - sulfuric is MUCH MORE dangerous
Really ??? --- nitric is "required" to process silver - & though not required is certainly preferred for gold refining AR
Here we go again with the sulfuric - which is BY FAR more dangerous then nitric --- & for what it is worth - you can recover your nitric by bubbling the nox fumes through H2O2 as well - which can as well be used for silver &/or base metal processing - thereby extending you (nitric) reagent value
I am sorry if what I have just posted sounds harsh - but some of what you have been posting here is at the very least "bad" information & in some cases actual mis-information & appears to simply be things you are posting here from watching to much You Tube which if full of bad &/or mis-information
So it is not my intent to be hash - but rather to make some corrections to what is clearly bad &/or mis-information being posted here
Kurt
Are we talking about the same IC chips? I have a bunch, the long thick rectangular old type, which absolutely have silver plating over brass. I even recovered silver from the plating. And on the inside, the bond wires were attached to little plates right at the tip of the 'arms' that are palladium plated over pure copper. Now, the chips came from very high-end industrial equipment made in the 1970's and 80's, so perhaps that's why? I have the consumer-grade ones too, and yes those are just kovar on the outside and aluminum-plated inside. I sort those differently. Those leads are magnetic. The high-grade ones I have separately aren't. I even have a handful of white-plastic-coated IC chips from a few old telecommunications CPU boards that were all gold inside when I cracked them open. As with all electronics, the super-expensive high-end stuff is WAYYYY beyond the 'garbage' sold to consumers, lol.
I even have some military-grade chips from specifically 1976, and those have a tremendous amount of silver and gold, and some canister IC transistors which are gold-plated inside and out, with the chip sitting on a bed of silver, and solid platinum electodes attached to the chip. Here's the inside of one I popped open today.
My descriptions of my protocols were highly incomplete, I was just making a rough list of topics. I burn all the chips first spread out in single layer on top of a steel mesh over a hot flame (except the ceramics, which are going to be a pain to crush and powder when I get to them) and then wash off the ash. I saw one vid you mentioned using sulfuric acid to dissolve the plastic, and I never thought that was a good idea. It's a waste of reagents, for one. And you end up with organic and metal acid sludge that's extremely toxic. The person doing that method was also clearly losing a lot of his PMs in other steps. The recovery was terrible. It's why I miss the downvotes on YT. I watched that one early last year, and only because I wanted to know why it had so many dislikes at the time. NOW it's hard for a beginner to judge if a method looks plausible or not, because YT decided to be dumb.
The newer flat chips mostly have tin solder, but I have found some that did contain bismuth solder. Those were very new chips, and upon looking into it, there was quite a push in the industry to use bismuth-based solders because of the low toxicity of bismuth salts, and because bismuth alloys so well with many metals (it can even be used for cupelling the same as lead, just more expensive; so it's sensible to recover it from the cupel). I was even able to turn it back to bismuth after it became goo in the rest tube, heating to decompose the nitrate, then reducing with carbon. I cooled it slowly in a little crucible inside hot bricks and sure enough, a little bit of the weird colorful and squarish bismuth crystal grew, just enough to confirm it. There's a reaction which takes place if the solution gets too warm during the reaction: it forms bismuth oxynitrate, also called bismuth subnitrate. I likely formed that because I had too little acid, since I was doing it in a test tube. This raised the pH above 1 while the solution was still quite hot and thus triggered the thermal decomposition of the bismuth nitrate.
And of course there's the indium solder found in some types of CPUs. It's tough to describe EVERY possible variation in one post!
I did somehow manage to turn silver plating into silver chloride in HCl in my test. Perhaps something else in the alloys of the base metal catalyzed it? Or could it simply be that the nano-layer plating was thin enough to completely react as the base metal was dissolved?
My mention of aluminum nitride goo is regarding aluminum brass used in some 'soft' gold-plated pins, which creates the aluminum nitride goo as the brass dissolves and frees the aluminum, which then becomes the nitride sludge. I happen to have quite a large number of that type of pin, again from that old industrial equipment where they are found in whole boards of connectors. Those I'll use HCl on, which dissolved the aluminum.
But I have other components that are complicated in construction with many tiny internal parts and clearly have aluminum brass with silver and gold plated bits, as well as little internal nano wires. I don't even know the names of these components, they were only on a specific box of boards I bought. I suspect they're some sort of control or regulator unit for a highly specific application.
Perhaps it's my biochemical background, but I'm far more worried about nitric acid's carcinogenic by-products and the contact explosives it can create (nitroglycerine, trinitrotolunene/picric acid, and many fulminates) than sulfuric acid's vapors and ability to eat up organic material, which I can deal with thanks to my training in handling strong acids (I've worked with chlorosulfuric acid in organic synthesis). I have lab-grade glassware in plenty, and several laboratory fume vacs, chemical-resistant tubing, and lab heating blocks and plates and ceramic-coated magnetic stir bars meant for use in corrosive liquids, so I can deal with SO2 vapor easily. In my state as well, government tends to raise eyebrows on people buying large quantities of nitric acid, due to the afforementioned boom-booms it is used to synthesize. It's NJ, and they are EXTREMELY hard to deal with. Simple fountain fireworks were illegal here for decades, for instance. Sulfuric is found in hardware store industrial-strength drain-cleaners, and isn't regulated as much as nitric here.
I've just found sulfate chemistry so simple to use. Oh, and the note of silver-palladium separation with sulfuric was just an off-note. In more detail, it's useful to pull BOTH metals out of a mix of parts, then cement on copper and THEN use nitric to redissolve them for further purification via silver chloride precipitation followed by palladium reduction methods.
I wasn't posting whole protocols, since each one is a full page long! My protocols (I was a biomedical genetics researcher for 17 years) tend to be quite exhaustive in detail. And they differ for every subclass of components I've sorted. I have no less than 2 dozen jars of different electronics, even different classes of pins, and each one has it's own protocol associated with it. I still have to completely subclassify the capacitors, of which there are dozens of types.
As you know, MLCCs alone have multiple types of metals on their ends: nickel, nickel-silver, silver, silver-palladium, and the rare 'holy grail' palladium-palladium ones. Thankfully, different-strength magnets do a good job of sorting them. Then there are the canister rolled foil-electrolyte types, most of which are aluminum, BUT some of the older ones also have a tantalum strip (and the double-ended ones which are often all tantalum, especially in the military-grade stuff I have), and I even found a handful of oldies with tell-tale purple-black tarnish on the leads which indeed was silver. Foil capacitors are a pain in the rear to sort. But tantalum is rocketing up in price, so I'm glad I saved them all. In fact, I just looked up tantalum prices again, and my jaw broke through the floor.