# Do any of these components contain Palladium?



## JaMora (Feb 17, 2022)

A big ask from the community!

Requesting if anyone knows from their own recovery experiences if any of the pictured items contain palladium (mostly ceramic disk capacitors).

I’ve numbered items so palladium containing items can be easily be called out. 

I know most of these will contain only Silver if anything.

I believe this will help a lot of us out but not if there is speculation or guessing 

I'll be researching via google as well before processing anything.

Thanks again GRF community!


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## MicheleM (Feb 17, 2022)

Hello! Maybe these videos could help







Increasing probability to find Pd Ag in items if they come from 1) very old equipment (1960-1995) 2) electronics for High-end applications, telecom, military or scientific , (until these days)


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## jhop1994 (Mar 17, 2022)

Lazersteve specifically had a comment about this to someone else and to summarize. Test them to find out, while the videos were educational about how to test. It clearly stated that these things vary from country to country.


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## JaMora (Mar 18, 2022)

Thanks @MicheleM for referencing those videos - I've watched them a few times over. The electronics he's working with differ a bit from what I find in the US which makes it difficult to trust 100% but definitely a resource of knowledge - such as the blue and yellow ceramic capacitors as these are very common internationally (new ceramic disk capacitors that are shiny and colorful - these are almost always going to contain only silver, as he proves in his videos).
In the end, you have the best advice:
"Increasing probability to find Pd Ag in items if they come from 1) very old equipment (1960-1995) 2) electronics for High-end applications, telecom, military or scientific"

After researching via Google for a few months and reading around forums - I've concluded basically the same information. A few tips and tricks to identify which components will 'most likely' contain precocious metals (Pd) other than silver:

1. Newer ceramic disk capacitor components made after roughly 1993 - 1995 will most likely contain only silver due to the push for replacing palladium with base metals in manufacturing ceramic disk and multilayer capacitors internationally during those years. 
In reference to disk capacitors, these newer components are pretty easy to identify simply from the manufacturing look - shiny, smooth, bright colors, etc. see example images #9, #11, #18, #19, #41, #42. 
Now compare these components to example images #10, 13, 16, 27, 43. These are obviously older and are only found on older electronics.

2. Keep components found on old electronics - Obviously you just don't find red, faded green, or grey ceramic disk capacitors on newer electronics - duh! throw them in the Pd bucket. 

3. Keep ceramic disk capacitors for Pd that look like they are one-off or not commonly found, even if found on newer electronics such as high-end technologies such as telecommunications, military, or medical. Some examples of these are example images #14, #16, #24, #28.

4. As for the commonly found tan/brownish ceramic disk capacitors, these are more difficult to categorize via appearance - more to follow on those but I've basically kept only those ones that are not black on the inside and have a lighter color - which this characteristic seems to correlate with the older tan/brown ceramic disk capacitors. 

5. If it's white inside - keep those components for Pd content. A bit off topic from ceramic disk capacitors but I did include example images #7 and #8 - I've heard many people say this about the white ceramic - I really don't have any good sources to reference other than individuals with first-hand experience in refining. For example, images #7 and #8 have a white ceramic plate inside with what looks to be printed circuitry via silver or palladium (or alloy of both) on ceramic.

Btw, I'm not throwing anything in the trash haha, everything I don't keep goes back to the individual who I get all of these electronics from. Everything will be processed one way or another. 

Funny thing is, I'm actually not even going after Pd, only Au. Really just keeping some of these components for when I master gold refining. Maybe one day I'll want a new challenge and I'll have a little bucket of components containing Pd stored up for that road. 

Hope this thread helps others who cherry pick these components. Not much information out there on ceramic disk capacitors.


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## orvi (Mar 18, 2022)

From the first sight, i cannot recognize any Pd ones on the photos. All apear modern, disc shape type caps, which could get you some silver, but i doubt Pd will be present. This is bit different technology than MLCCs. Many times using silver plated ceramics, many times just base metals. Old basic ceramic capacitors - not MLCCs - from 60-80s (eg TESLA or USSR/Bulgarian types) contain up to few % of silver some times, but generally less than 10g/kg. Too much labor, dealing with tin and quantities of nitric. For me not economical. But if you manage to get some few kilograms, smelting it with added lead could produce nice dore.

#24 look very intriguing... but it needs testing. If it is Pd type, nitric test could generally reveal it by just looking at the colour of the leaching solution (if Pd content is decent). More sensitive test is DMG. Even if you cannot see yellow precipitate, you can filter the solution through a filter paper and any very fine precipitate should be clearly visible.


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## JaMora (Mar 18, 2022)

Thanks @orvi, I'm very familiar with all types of multi-layer capacitors. This post was more so focused on the disk capacitors. 
The older ceramic disk capacitors definitely used Pd. The machinery that made the pre-1990s ceramic disk capacitors were engineered specifically for use with either silver or a palladium/silver alloy for the electrode coated on the ceramic dielectric. Base metal materials weren't used until the machinery was developed to do so and implemented around 1993 through 1995 for big industry. This goes for MLCCs as well from what I've learned. This said, I know most standard ceramic disk capacitors still only used silver alone. But the unique ones definitely used the Ag/Pd alloy. 

Mid 1990s was the big shift towards using base metals for components used in standard electronics. Some manufactures didn't shift over until the late 1990s due to the cost of acquiring new manufacturing equipment - which is why a lot of automotive companies such as Mercedes or GM still had none-magnetic MLCCs in their automotive computers up until the late 1990s. 

Haha yeah if you think # 24 is interesting, you should have seen the boards it came off of. It was an early 1980s automotive emissions computer from an automotive shop. The boards that #24 came off of were HP circuit boards completely gold traced. All together, from one computer, the gold foils filled a 120mm Buchner funnel filter similar to 3 kilograms of ram fingers! They looked a lot like this but without those newer ICs and instead, fully analog. 


Thanks for the refining tips, but I'm only collecting Pd scrap as of now (or at least what I think is Pd). It will probably be a few years before I even think to begin any of those processes - maybe I'll contact you one day in the future with a bunch of questions haha jk. Lots of learning ahead.


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## orvi (Mar 18, 2022)

Yes, you are right. I forgot the USSR red square ceramics, which used to contain PdPt. Generally i have experience with the classic type "brown ones" manufactured mainly by TESLA. These have relatively OK silver, but not economical for me.

Haha, yea, that´s the stuff! I once acquired like 20-30 cards from old PC´s, like 60-80´s. The thickness of plating on the fingers was just impressive. The fingers were apparently plated manually, not in an automated process.

The value of this type of stuff will only go up as the time pass. So if you have place where you can store it, good way to go. 

It is pretty obvious if you have MLCC, crack one with pliers and if you see ceramic, celebration starts  not only eastern-type electronics have good MLCCs. Also old western equipment have them. 

PS: on the photo of board you send, there are small yellow components, looking like resistors. Crack one with pliers - I have seen quite a bit of these, and they used to be MLCCs too. Some plastic, some like resin dip packages 
And also two good sized tantalums. But probably no solid-silver casing.


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## MicheleM (Mar 18, 2022)

JaMora said:


> Thanks @orvi, I'm very familiar with all types of multi-layer capacitors. This post was more so focused on the disk capacitors.
> The older ceramic disk capacitors definitely used Pd. The machinery that made the pre-1990s ceramic disk capacitors were engineered specifically for use with either silver or a palladium/silver alloy for the electrode coated on the ceramic dielectric. Base metal materials weren't used until the machinery was developed to do so and implemented around 1993 through 1995 for big industry. This goes for MLCCs as well from what I've learned. This said, I know most standard ceramic disk capacitors still only used silver alone. But the unique ones definitely used the Ag/Pd alloy.
> 
> Mid 1990s was the big shift towards using base metals for components used in standard electronics. Some manufactures didn't shift over until the late 1990s due to the cost of acquiring new manufacturing equipment - which is why a lot of automotive companies such as Mercedes or GM still had none-magnetic MLCCs in their automotive computers up until the late 1990s.
> ...


Man, this circuit board is a masterpiece, I would append it to the wall like a painted picture.


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## Geo (Mar 18, 2022)

Dusan is from Serbia and most of his electronics are old Soviet hardware. Very rich in precious metals compared to the USA equivalent components of the day. Most of the disc capacitors have no precious metal value using MgO for capacitance. There are the few but it's very hard to tell the good ones from the bad.


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## orvi (Mar 19, 2022)

I am also from former Soviet country and sometimes also enjoy having possibility to acquire some very solid stuff. Plated fingers with so thick foils, that do not bend when you swirl the beaker  etc...
Pins from sockets or connectors that rarely run under 10g/kg. You need to know every single component on the boards, just to not throw away some values. Old potentiometers with palladium plated parts, palladium plated traces on boards (if you have very old board with "silver" traces, there is high chance it´s actually palladium) and so on.


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## kurtak (Mar 19, 2022)

Awesome thread guys !!!!



orvi said:


> Plated fingers with so thick foils, that do not bend when you swirl the beaker  etc...
> Pins from sockets or connectors that rarely run under 10g/kg.


Yap - I have run across stuff like that (5 grams per pound - or 10 plus grams per kilo)

Talk about foils - it's quite a site to see foils so thick they actually look just like the pins "before" dissolving the base metal away

plating so thick the acid has a hard time working on (dissolving) the base metal even putting the acid on a simmer boil

It's plating dreams are made of 

Kurt


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## orvi (Mar 19, 2022)

Connector on photo above is called URS. Male part have pins running 9g/kg. Female part 14g/kg. These are quite common in old equipment here. It just underlines how ineffective the Soviet era manufacture was. It was rated for several amps, yet used as standardized connectors like everywhere, occupying so much space where completely unnecessary, used even for few mA connections... Completely wasteful, unnecessarily heavily plated. Third of the gold will be perfectly sufficient  26 pins in each piece. Female weighing around 0,4g, male 0,33g. Over 0,2g of gold per complete connector. In old "box" PCs, there were more than 20 pairs of them. Just speaking of connectors for cards... It impress me every day how this was even possible to manufacture in that quantity...
SNP connectors made in USSR were running up to 27g/kg... processing the unsoldered connectors with nitric acid was practically impossible. You need to go straight AR on them.
But I do not argue, better for me  sadly, this type of material is exceedingly rare these days.
Not to mention cards like one on the picture below  literally covered in palladium. Everywhere. Value of these pieces in triple digits just in today´s PM value.


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## MicheleM (Mar 19, 2022)

27 g/Kg ??? Why such a insane plating? Perhaps they were suppose to survive the high radiation fluxes coming from nuclear blast


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## orvi (Mar 19, 2022)

MicheleM said:


> 27 g/Kg ??? Why such a insane plating? Perhaps they were suppose to survive the high radiation fluxes coming from nuclear blast


Yup, very hard to understand why it was so thick  maybe because Soviet headmasters said "we can, and we will have the thickest plating on Earth!" Engineer: "But, sir, it just add weight to our equipment and drain our country and citizens from resources..." "I say that again, triple the necessary plating, for the glory of our empire!"  when I processed this type of material ordinarily, it came in big mixed batches of everything. Straight AR processing. I did not take pictures at that time, but if you know OwlTech, he has many many great videos about practically the same stuff. Thrilling to watch the gold drop from like 2 kilos of pins  getting to the 6-7th spoon of SMB and solution still has yellow tinge to it  ... wonderful times


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## silver1 (Mar 19, 2022)

orvi said:


> Yup, very hard to understand why it was so thick  maybe because Soviet headmasters said "we can, and we will have the thickest plating on Earth!" Engineer: "But, sir, it just add weight to our equipment and drain our country and citizens from resources..." "I say that again, triple the necessary plating, for the glory of our empire!"  when I processed this type of material ordinarily, it came in big mixed batches of everything. Straight AR processing. I did not take pictures at that time, but if you know OwlTech, he has many many great videos about practically the same stuff. Thrilling to watch the gold drop from like 2 kilos of pins  getting to the 6-7th spoon of SMB and solution still has yellow tinge to it  ... wonderful times


Maybe you guys can read this then. A member posted this on the forum years ago whom was from Russia. I've had it in my library even though i can't read it.


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## orvi (Mar 19, 2022)

silver1 said:


> Maybe you guys can read this then. A member posted this on the forum years ago whom was from Russia. I've had it in my library even though i can't read it.


Nice doc, altough I never stumbled across these USSR IC chips. I do not know how it is possible, through few years doing kilos of materials.
I do not speak russian, nor read in azbuka very well. My language is slavic, so it is distantly similar tho.
Important words you need to read this document:

золото = (zoloto) = gold
масса = (massa) = weight
изделия = (izdelija) = products/product
серебро = (serebro) = silver
палладий = (palladij) = palladium
металличеиской = (metalličeiskoj) = metallic
фракции = (frakcii) = fraction
соответствие с паспортными данными = (sotvectvie s pasportnymi dannymi) = accordance with data (very rough translation, im not sure)

Hope this lame "key words manual" could guide you through


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## BlackLabel (Mar 19, 2022)

Hi,
Here are three more helpful words for this document:

платина = platinum
шт. = pc. (piece) / pcs. (pieces)
г / грамм = g / grams


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## orvi (Mar 19, 2022)

BlackLabel said:


> Hi,
> Here are three more helpful words for this document:
> 
> платина = platinum
> ...


Yeah, forgot to add the basic stuff  anyway... Hope to use this document some time in the future  these components are not so common to stumble across :/


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## BlackLabel (Mar 19, 2022)

Orvi,
Where are you from?
I'm from Germany.
I started trying learning Russian because there are a lot of interesting videos about refining from Russia. I think the Kyrillic writing is easy as long you can convert the letters (реактор = Reaktor in German | Ctoп = Stop).
Listening to the spoken language is hard.

Best regards from Germany.


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## Owltech (Mar 20, 2022)

It's simplified BOM (bill of materials) regarding the type and quantity prescious metals used in different products


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## Alondro (Mar 27, 2022)

orvi said:


> Yes, you are right. I forgot the USSR red square ceramics, which used to contain PdPt. Generally i have experience with the classic type "brown ones" manufactured mainly by TESLA. These have relatively OK silver, but not economical for me.
> 
> Haha, yea, that´s the stuff! I once acquired like 20-30 cards from old PC´s, like 60-80´s. The thickness of plating on the fingers was just impressive. The fingers were apparently plated manually, not in an automated process.
> 
> ...


Do you happen to know what the 'silver' plating is on 80's and early 90's pins and contacts, which is sometimes in place of gold plating? It's very bright plating, and doesn't look like tin at all. I've heard that thin plating of Pt-group metals will dissolve in conc. HCl. If that's true, can I dissolve a few and then stannous test them?


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## Alondro (Mar 27, 2022)

orvi said:


> Yup, very hard to understand why it was so thick  maybe because Soviet headmasters said "we can, and we will have the thickest plating on Earth!" Engineer: "But, sir, it just add weight to our equipment and drain our country and citizens from resources..." "I say that again, triple the necessary plating, for the glory of our empire!"  when I processed this type of material ordinarily, it came in big mixed batches of everything. Straight AR processing. I did not take pictures at that time, but if you know OwlTech, he has many many great videos about practically the same stuff. Thrilling to watch the gold drop from like 2 kilos of pins  getting to the 6-7th spoon of SMB and solution still has yellow tinge to it  ... wonderful times


I got some pins from nuclear launch control boards made in 1976. The gold plating is so thick that when the beryllium-copper cores are dissolved, the gold foils sit there as hollow tubes! They don't even drift much when you swirl the solution. They sink right back down almost as soon as you stop shaking the the flask (gotta be SUPER careful with those solutions! Beryllium ion is very toxic, interfering with many enzymes which require Mg in their reaction centers, as well as blocking DNA synthesis in cells; and the body can't eliminate it because it's such a tiny ion and highly charged, so it accumulates!)


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## Alondro (Mar 27, 2022)

JaMora said:


> Thanks @orvi, I'm very familiar with all types of multi-layer capacitors. This post was more so focused on the disk capacitors.
> The older ceramic disk capacitors definitely used Pd. The machinery that made the pre-1990s ceramic disk capacitors were engineered specifically for use with either silver or a palladium/silver alloy for the electrode coated on the ceramic dielectric. Base metal materials weren't used until the machinery was developed to do so and implemented around 1993 through 1995 for big industry. This goes for MLCCs as well from what I've learned. This said, I know most standard ceramic disk capacitors still only used silver alone. But the unique ones definitely used the Ag/Pd alloy.
> 
> Mid 1990s was the big shift towards using base metals for components used in standard electronics. Some manufactures didn't shift over until the late 1990s due to the cost of acquiring new manufacturing equipment - which is why a lot of automotive companies such as Mercedes or GM still had none-magnetic MLCCs in their automotive computers up until the late 1990s.
> ...


I've got to get some info on those big old block-type capacitors, the large rectangular red, brown, and blue ones. They have a foil of some type inside them. The smaller ones are a mix of foil wrapping type, and solid-ceramic type that look like resin-coated early-generation MLCCs. 

And then there are the potential tantalum capacitors... there are so many possible ones, I have a jar filled with DOZENS of types of capacitors which MIGHT have tantalum. The only ones I'm certain of are the tantalum-drop type and the little yellow and black rectangles from 90's boards.


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## kurtak (Mar 27, 2022)

Alondro said:


> And then there are the potential tantalum capacitors... there are so many possible ones, I have a jar filled with DOZENS of types of capacitors which MIGHT have tantalum. *The only ones I'm certain of are the tantalum-drop type and the little yellow and black rectangles from 90's boards*.


Per the bold print - read this thread - it will help you identify most if not all types tantalum caps









Tantalum Capacitor Scrap Purchasing -- International


Tantalum Capacitor Scrap Purchasing -- International We purchase all types of Tantalum Capacitors Scrap Epoxy/Ceramic Capacitors - $24.45/Lb SMD Capacitors -- $24/Lb Hermetic Capacitors - $23.65/Lb Wet Tantalum Capacitors - $50/Lb Ag/Ta Capacitors - $75/Lb We purchase all quantities small and...




goldrefiningforum.com





Kurt


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## kurtak (Mar 27, 2022)

Alondro said:


> I've heard that thin plating of Pt-group metals will dissolve in conc. HCl. If that's true, can I dissolve a few and then stannous test them?


Pd is the only PGM that will dissolve in HCl alone - BUT - in order to do so the Pd has to be *VERY* finely divided (*ULTA* fine)

I don't believe Pd plating is fine enough for HCl to dissolve it

To put it somewhat in perspective

I have used HCl to wash Pd cemented from solutions (which is a VERY fine powder) without putting Pd back into solution

On the other hand - when I was leaching catalytic converters for their PGMs - the Pd is so ULTRA fine that the Pd would go into solution almost instantly when pouring the HCl into the CAT combs --- in other words put Pd in solution with just HCl & before adding chlorine --- but as I say - the Pd in the wash coat of CATs is ULTRA fine (much finer then cemented Pd)

The Pt & Rh in CATs is just as fine as the Pd - but nether Pt or Rh would go into solution with just HCl

In order to dissolve the VERY finely divided Pt & Rh in the CATs it required HCL plus chlorine

Kurt


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## Alondro (Mar 27, 2022)

kurtak said:


> Pd is the only PGM that will dissolve in HCl alone - BUT - in order to do so the Pd has to be *VERY* finely divided (*ULTA* fine)
> 
> I don't believe Pd plating is fine enough for HCl to dissolve it
> 
> ...


Thanks! I'm always nervous about soaking plating in concentrated acids when I don't know what the metal is, or exactly how it reacts. So if the plating dissolves easily in HCl, it's probably nothing of value. That'll be useful for determining which of the 'silver' plated pins to process.


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## Alondro (Mar 27, 2022)

Here are some pics of my various sorted capacitors (and some other disc-type components), which COULD be Ag-Pd, Ag, or just junk! I'll put the potential (and some known) tantalum types in a second note. 

#20 in the second picture has the 'unique' types, and those are the only ones I have of those types/colors.


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## Alondro (Mar 27, 2022)

And now the 'tantalum' types. Many of these I'm not sure what the foils inside are composed of. But the pics can be labelled by the experts as to what they most likely have in them, which will be helpful for everybody. 

All of these were from boards acquired in the USA, most of the old-types were made in Japan, Taiwan, or the USA. A few from Mexico, Philippines, and Malaysia. Most of the new types were from boards made in China.

#17-20 are the ones I'm CERTAIN are tantalum (though the little black rectangles might have some Schottky diodes mixed in). #19 are the nice little tantalum drops, and #20 are military-grade tantalum tube capacitors from the late 1970s. They're very heavy compared to the others and the metal is quite hard. From what I could find about them, apparently even the casing is tantalum! They were made for very high-voltage circuits. I got them off the launch control boards I've mentioned in other posts. You'll never find them on consumer electronics, not even in most industry. Only aerospace and military. The large foil types in #10 also came from those boards, but I'm not certain what metal foil combinations they use. Those old foil capacitors were quite varied, especially when you get them from ultra-high-grade equipment.


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## Alondro (Mar 27, 2022)

One more pic with some more 'unique' capacitors, maybe tantalum, maybe silver, maybe nothing but aluminum! 

I think the little drop ones are tantalum. They're heavy for their size. But maybe another heavy metal too.


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## orvi (Mar 28, 2022)

I came across silver and palladium plated contacts and pins, aside of dip-tin coating as well. Distinguishing between Pd and Ag on older boards, which were sitting somwhere for long time, is most of the times very quick. Silver tarnish the way you cannot mistake. Palladium don´t.


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## orvi (Mar 28, 2022)

Alondro said:


> Here are some pics of my various sorted capacitors (and some other disc-type components), which COULD be Ag-Pd, Ag, or just junk! I'll put the potential (and some known) tantalum types in a second note.
> 
> #20 in the second picture has the 'unique' types, and those are the only ones I have of those types/colors.
> 
> ...


#8 - written NTC - this is a thermistor - type of resistor, used in soft-start circuit of power supply. In terms of precious metals, i don´t know if it contain something valuable. 

I see plenty of classical ceramics and then plenty of foil ones. I maybe dissapoint you, foil caps are aluminium foil and some dielectric plastic wrapped together. No value.
Luckily, they are very easy to distinguish from others - they are very light, have distinct shapes when resin-coated, and after cracking one open, it is clearly visible


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## orvi (Mar 28, 2022)

Alondro said:


> And now the 'tantalum' types. Many of these I'm not sure what the foils inside are composed of. But the pics can be labelled by the experts as to what they most likely have in them, which will be helpful for everybody.
> 
> All of these were from boards acquired in the USA, most of the old-types were made in Japan, Taiwan, or the USA. A few from Mexico, Philippines, and Malaysia. Most of the new types were from boards made in China.
> 
> ...


The plastic casing ones are 90+% foil ones. If you see markings like "MKP" or "X2", thesse mark classes of foil capacitors. These are often found as filtering caps in power supply used for noise reduction - switching power supply in general create a lot of high frequency noise in kHz range, and it should be filtered very good. Otherwise it will pass to the grid in your house and cause for example TVs and audio amplifiers to catch that noise and mess audio/video quality. 
Also, they are very light, distictivly shaped, and inside you find just foil  some brands are quite expensive, but used ones, I do not know if there is any retail value in them. In power applications, they go through harsh conditions, and this could result in permanent damage, which is very hard to asses without special cap meters and ESR meters.

Next you have some classical electrolytic caps there. Electrolytic vs. tantalum is also easy to distinguish after some practice. Elyte is made of aluminium with just electrodes (also aluminium largely) and some paper inside = very light. Tantalum contain tantalum of course = very dense metal. And casing is usually made from silver plated brass (if it is the old type). Very old ones could have solid silver casings.
"Drop" like resin-dipped things could be tantalum. But this shape is also common to be old-manufactured coils. Snap one open and you will see. In tantalum, you will find actual tantalum electrode and silver foil. In the coil... Wire you find


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## kurtak (Mar 28, 2022)

#10 are also Ta --- #15 - maybe - not sure - the pic gets blurry when I try to enlarge it 


Alondro said:


> *#20 are military-grade* tantalum tube capacitors from the late 1970s. They're very heavy compared to the others and the metal is quite hard. From what I could find about them, apparently even the casing is tantalum! They were made for very high-voltage circuits. I got them off the launch control boards I've mentioned in other posts. *You'll never find them on consumer electronics, not even in most industry. Only aerospace and military*


Per the bold print --- not true - I have pulled those off of MANY different OLD boards that most certainly were NOT military/aerospace

Kurt


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## Alondro (Mar 28, 2022)

orvi said:


> I came across silver and palladium plated contacts and pins, aside of dip-tin coating as well. Distinguishing between Pd and Ag on older boards, which were sitting somwhere for long time, is most of the times very quick. Silver tarnish the way you cannot mistake. Palladium don´t.


Oooo... wow... many of these pins are bright and shiny, even after they've been sitting for decades. This is very promising!


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## Alondro (Mar 28, 2022)

orvi said:


> The plastic casing ones are 90+% foil ones. If you see markings like "MKP" or "X2", thesse mark classes of foil capacitors. These are often found as filtering caps in power supply used for noise reduction - switching power supply in general create a lot of high frequency noise in kHz range, and it should be filtered very good. Otherwise it will pass to the grid in your house and cause for example TVs and audio amplifiers to catch that noise and mess audio/video quality.
> Also, they are very light, distictivly shaped, and inside you find just foil  some brands are quite expensive, but used ones, I do not know if there is any retail value in them. In power applications, they go through harsh conditions, and this could result in permanent damage, which is very hard to asses without special cap meters and ESR meters.
> 
> Next you have some classical electrolytic caps there. Electrolytic vs. tantalum is also easy to distinguish after some practice. Elyte is made of aluminium with just electrodes (also aluminium largely) and some paper inside = very light. Tantalum contain tantalum of course = very dense metal. And casing is usually made from silver plated brass (if it is the old type). Very old ones could have solid silver casings.
> "Drop" like resin-dipped things could be tantalum. But this shape is also common to be old-manufactured coils. Snap one open and you will see. In tantalum, you will find actual tantalum electrode and silver foil. In the coil... Wire you find


I popped open a few multi-colored drop ones, no coil inside! Just silvery metal foil surrounding a ball of dark, compressed metal powder. Silver and tantalum! Yay!

Some of the foil inside several of the plastic rectangle (metalized polypropylene) capacitors is strange. It doesn't look like aluminum. It's steel-colored and stiff, and when you bend it, it flexes back to a sheet again, whereas aluminum crumples. At the ends of a foil coils is a powdered metal pressed into a cap. The others that are clearly aluminum don't have this. I'll have to do a few chemical tests on a piece of it.

EDIT: Testing some foils from a few of the uncertain capacitors in HCl showed some dissolved instantly, so those are Al. But others, namely from the 'plastic box' polypropylene type, have the wide foil dissolve at once (Al), but the narrow middle foils are dissolving more slowly and leaving a black powdery material, possibly that metal is dissolving and then reducing as the Al foil dissolves. Maybe a tin metallized plastic strip? Zinc 'schoopages' (just found that term)?

The few small yellow rectangle capacitors that have the stiff, darker foil in flat stacked layers are probably zinc on a type of harder plastic. That was apparently used in some of the metallized plastic types. 

Also found out that the tiny black plastic rectangle capacitors can be niobium/niobium pentoxide instead of tantalum. 

As for the many types of ceramic discs, I might as well process all of them. The electrodes appear to frequently use silver, at the very least. The oldest ones may also use an Ag-Pd alloy.


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## kurtak (Mar 29, 2022)

Alondro said:


> I popped open a few multi-colored drop ones,


Yes those are tantalum caps


Alondro said:


> Just silvery metal foil


I believe the foil is tantalum (yes they make tantalum foil)


Alondro said:


> surrounding a ball of dark, compressed metal powder.


That is for sure the (sintered) tantalum pellet

Kurt


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