# Schottky Barrier Rectifiers



## resabed01 (Feb 23, 2013)

Been doing some online reading about these diodes and interestingly enough, I see there is a possibility they can contain Pt or Pd. Not in the bond wires or the die to substrate bond but in the die itself as part of the semiconductor element.
These diodes exist in practically any modern switch mode power supply. Open up any computer power supply and you'll find two or more that have sizable current rating (higher current rating = larger die size)

Anybody worked with this scrap and experienced PGMs?

http://en.wikipedia.org/wiki/Schottky_diode


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## Captobvious (Feb 23, 2013)

Not sure about the pic on top but the ones on the bottom look like Tantalum, may want to do a search for those as I know those are worth money but not sure how much, so they just get tossed into a jar for now until I get enough to figure out what to do with them, and be worth my while.


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## resabed01 (Feb 23, 2013)

I just pulled the pictures from Google Images. I know they look like Tantalum caps but they are surface mount diodes of the Schottky type. I've seen these in TV and monitor power supplies.


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## Findm-Keepm (Feb 23, 2013)

resabed01 said:


> I just pulled the pictures from Google Images. I know they look like Tantalum caps but they are surface mount diodes of the Schottky type. I've seen these in TV and monitor power supplies.



Schottky diodes are cheap, so if there are any precious metals within, they are in trace amounts. The die is fused to the copper directly, as several amps have to pass through them. Wimpy die connect wires aren't used. 

Probably more copper value than PMs. 

BTW - Be careful in posting photos that are not your own - my employer just won a settlement for unauthorized use of some photos from our servers. Googlebot did a drive-by and got them to Google where they gave credit, but the Florida entrepreneur that was too lazy to produce his own images for his website didn't, and now has a low 5-figure judgement and lawyer fees.  

Brian


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## Findm-Keepm (Feb 23, 2013)

After some further reading spurred by the OP's comments, there are some types that use PMs, including gold.....

http://www.micross.com/pdf/GB20SHT065-CAU.pdf

I wonder what the yield would be from 1Kg or so of these. Lotsa copper for sure, but perhaps _multiple_ PMs...

Brian


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## Marcel (Feb 24, 2013)

I have around 40kg of them (mixed types) currently going trough a large refiner here in germany. I have not seen the analysis data so far, but expect them for next week. I will post them once I have them.
I expected Pd and Ag. I am surprised to learn that they may contain Pt. That would be great, since over 95% of the mass is copper for which I dont get any credit for.
Also I did not expect a lot. There are basically 2-5 bondwires and a little bit silver that is used to solder the die on the copper heatspreader. But you never know!

Marcel


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## resabed01 (Mar 7, 2013)

It will be interesting to see what comes back from this Marcel, Thanks!


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## johnny309 (Mar 29, 2013)

Sorry...but it is not as the detailed datasheet explains...so:
1.In the original PDF(....let's say SEMIKRON..)..it can be posible ,but the cheap copy from China.....I think not
2. The same type have different termination number....so....maybe ...the one's that are meant for military use or medical use can benefit from the use of precious metals in their use.

I really don't think that the one we encounter in PC power supplies contains a metal more expensive than copper.....maybe except Sn(tin)...from the soldered leads...


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## ilikesilver (Apr 27, 2013)

Found this interesting last night. I remembered this post and searched for it, didnt want to reactivate a dead one, but thought it was interesting anyways. seems to be gold overlay on copper on the left. the center you can see the redish copper color of the plate and on the outsides seems to be gold plating. tim


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## ilikesilver (Apr 28, 2013)

is anyone checking these little buggers, they are pretty numerious on boards. any thoughts tim


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## macfixer01 (Apr 28, 2013)

ilikesilver said:


> Found this interesting last night. I remembered this post and searched for it, didnt want to reactivate a dead one, but thought it was interesting anyways. seems to be gold overlay on copper on the left. the center you can see the redish copper color of the plate and on the outsides seems to be gold plating. tim




These are a different type of device than what the thread was opened about but the packaging is similar. The IRFxxx part number indicates to me they're FET's or field effect transistors. These are used a lot for example in printer boards, like for driving dot-matrix print heads or driving the phases of the different stepper motors. When I strip a board I always crack open any sort of transistor type device, at least one sample of each type. Then if they have no visible gold inside, any identically numbered parts can be scrapped. Unless you discover they contain other PM's of course.


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