PMs in Surface Mount Components

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tlcarrig

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Nov 14, 2007
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Well, I have done my searches and have not found anything definative on the subject. What PMs could I expect to find in surface mount resistors, caps and diodes? I know that flat packs are a toss up as to what might be in them. Also, what is the majority of the solder used now days? Is it silver, tin/antimony or tin/lead? I am getting ready to start depopulating my boards and need to know when to stop. No need in harvesting something that is of no value. Thanks in advance for any info.
 
Capacitors can have silver, palladium, and some other metals.
I dont know about diodes, transistors.
 
PM's in SMD's mostly resistors and there was a few caps in there, 100% off tape reels dated late 90's.
Total material dry weight was about a 1 pound (16oz).
Material sat outside in the sun for near a month while removing any tin/lead solder in HCl bath being stirred from time to time and changed out for fresh HCl while removing base metals.

Tested stannous, palladium and some slight platinum maybe.
When dropped with zinc I noticed the palladium sank very quickly.
Pulled all the palladium out and tested the pour off (addidtional zinc added) and got some more. Again another test and additional zinc, and appears maybe 1/2 gm of platinum (I think) fine powder material and just over 8gm palladium powder.

The pic shows the palladium powder removed.
The HCl/Cl wash out with super deep red stuff on left with most of values and still pretty deep color on right as I leached out the components.
 

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Nice work Adam.

Main problem with resistors is their Alumina/silicon substrate, i'm afarid, by not crushing them, you probably won't reach all of the PM's in them (Ag/Pd).
Unlike SMD capacitors that utilise Barium titanate as substrate and is slightly soluble in acids, Alumina/silicon are practically inert to mineral acids.

You should also take into account that some of resistors types contain RuO2 as the resistive layer, though i'm not so sure how will it react with the HCl, if at all.
The Ru is not worth the hassle, that's for sure. But it will be good to know if and how will it effect the process. Great caution should be taken in either cases.

It will be nice to see your progress with this project.
 
Can palladium be concentrated or recovered using quartz sand / NaO3 (flux) / borax and fired in a crucible? I saw this neat trick were guys are making gold dore' from a mix like that w/ black sand concentrates and putting all in a microwave oven to melt it in a little crucible. Could that be done with palladium? I was even thinking of panning or shaker table separating my crushed MCCs to try and remove some of the ceramic materials ... or at least to try and get higher concentrations of palladium in one portion of the feed material.

I don't mind using HCL to dissolve base metals, but I just don't want to deal with acquiring, storing, and disposing of all the other acids.

I have about 1400grams of MCCs to play with (2007 era, newer unfortunately) off some video surveillance equipment. I think the boards are pretty high grade because all exposed metal on the whole card is gold plated. But I don't know if that will carry over to palladium content of the MCCs.

I'd be happy to get a Pd / Ag button as I'm not interested in producing something to sell ... just want it to be non-tarnishing PM.

Any suggestions?
 
My concern with collecting values in melt would be getting flux right to make all that ceramic fluid. and not melting my melting vessel into a blob.

acids would be the easy approach in my mind.
 
yes, a big part of my idea is to mechanically separate out most of the ceramic material ... but I don't know if that's possible yet. Pd does have a density near lead, so I was hoping to at least be able to use gravity and vibration to concentrate a sample. Maybe I'm going to be trying something new here, and I'll be sure to let everyone know how it goes ... even if a flop.
 
I found a link that may be helpful on the MCCs:

http://www.johansondielectrics.com/technical-notes/product-training/basics-of-ceramic-chip-capacitors.html

especially down at the bottom of the page, there is some explanation of markings associated with these ... sorry, haven't had a chance to check to see if the markings are actually on the device, but there is a letter dedicated to the materials used which might be a tip off to PM content.

Also, it said that MCCs rated for over 500VDC usually still have Palladium.
 
jdat747 said:
I found a link that may be helpful on the MCCs:

http://www.johansondielectrics.com/technical-notes/product-training/basics-of-ceramic-chip-capacitors.html

especially down at the bottom of the page, there is some explanation of markings associated with these ... sorry, haven't had a chance to check to see if the markings are actually on the device, but there is a letter dedicated to the materials used which might be a tip off to PM content.

Also, it said that MCCs rated for over 500VDC usually still have Palladium.
Click to expand...


What a nice link, thank you.
 
samuel-a said:
Nice work Adam.

Main problem with resistors is their Alumina/silicon substrate, i'm afarid, by not crushing them, you probably won't reach all of the PM's in them (Ag/Pd).
Unlike SMD capacitors that utilise Barium titanate as substrate and is slightly soluble in acids, Alumina/silicon are practically inert to mineral acids.

You should also take into account that some of resistors types contain RuO2 as the resistive layer, though i'm not so sure how will it react with the HCl, if at all.
The Ru is not worth the hassle, that's for sure. But it will be good to know if and how will it effect the process. Great caution should be taken in either cases.

It will be nice to see your progress with this project.
Click to expand...


If you are after Pt/Au/Ag/Pd you don't have to worry about the ceramic core of the resistor as it is only a substrate/bedding to the actual resistive layer. Mentioned PMs can be found (not in every SMD resistor) only on the pads (metallized ends). The resistive layer can contain Ta, Ru or Ir, it sits on top alumina bedding and is accessible to chemicals without destroying bedding.
If one would really want to destroy the alumina bedding it can be filtered after leaching with acids and dissolved in NaOH.
Al2O3 dissolves in NaOH quite easily leaving any metallic impurities as a sludge.
It is actually an industrial process of purifying alumina (don't remember the name of inventor).

I haven't heard of silica/silicon being used as substrate, but even that could be dissolved in NaOH (got to be very hot :shock:) and as a result you'll get "liquid glass" :mrgreen:



Speaking of which.
There is a chance of reducing bulk of resistors mass (maybe also capacitors - depending how BaTiO3 would react with NaOH), getting rid of epoxy overcoat and getting rid of Sn at the same time by using NaOH as a first leaching agent. Some heat might be required.



:!: :!: :!: Whoever plays with SMD scrap be careful - Barium is pretty nasty element, safe only as BaSO4 :!: :!: :!:
 
If you get a very pretty dark blue in your NaOH hot leach, the chances you have colbalt, just like i encountered, well my assumption is that it's colbot, found a small empty button battery bits in the starting ash.

Cobalt.JPG

Deano
 
Cobalt, its a real chameleon, nearly every salt has different colour and all the colours are very deep and rich.
My favourite salts when establishing "chemical garden" with Na2SiO3 :mrgreen:
 

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