# Palladium plating on pins of common 7400 series ICs?



## Auggie (Aug 5, 2012)

I was reading this datasheet today for a project I'm working on and found an interesting footnote. Look on the lower left-hand corner of page 5: "* Pd plating"

http://pdf1.alldatasheet.com/datasheet-pdf/view/64008/HITACHI/74LS164.html


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## Irons2 (Aug 5, 2012)

Those surface mount devices are quite small. Look for the ceramic ones from the 70's. Those flatpacks have some worthy Pd plating.


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## Auggie (Aug 5, 2012)

Irons2 said:


> Those surface mount devices are quite small. Look for the ceramic ones from the 70's. Those flatpacks have some worthy Pd plating.



Aha. I didn't notice that was a surface mount version.

Are you saying all the DIP package type ICs have palladium plating on the legs?

http://www.twistywristarcade.com/182-505-large/74ls152.jpg


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## Irons2 (Aug 6, 2012)

Auggie said:


> Irons2 said:
> 
> 
> > Those surface mount devices are quite small. Look for the ceramic ones from the 70's. Those flatpacks have some worthy Pd plating.
> ...


Lead/Tin solder is more likely. Surface mount devices might have a PM coating to aid soldering, since the process is different than thru-hole boards, but even those are likely to be solder plated. I used to do surface-mount rework as part of my job as a Diagnostic Tech for Digital Equipment Corp. Most of what I saw looked like solder, not PM. Even if it was a PM plating, the value would be very little. If you had a large quantity of parts, it would be worth processing, otherwise, it's just a curiosity.


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## NoIdea (Aug 6, 2012)

One of those uncertain area's, not sure if there are PM's in them their bits. When it comes to IC's this is roughly how i do it, more detailed poste will follow as soon as i finally figure out what im doing. :mrgreen: 

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=15086&p=152651#p152651

Cheers

Deano


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## macfixer01 (Aug 9, 2012)

As Irons2 said, lead/tin solder coating was the norm. However I've seen many old 7400 series chips from the early 1970's which have their pins turned black and/or are coated with a powdery black material (mostly Texas Instruments brand as I recall). I have to assume maybe they were silver plated, which turned into silver oxide or silver sulfide over the years?

Edit - I meant to say this is for the through-hole DIP type packages.


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## NoIdea (Aug 9, 2012)

macfixer01 said:


> ....I have to assume maybe they were silver plated, which turned into silver oxide or silver sulfide over the years?
> 
> 
> > You are right on about it being silver and easy to spot on the older stuff. Well spotted :mrgreen:
> ...


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## tek4g63 (Aug 9, 2012)

I worked manufacturing electronics for 13 years. Most components with silver colored leads were referred to as " tinned". A heavy tin based solder was lightly coated on them to prevent oxidation from forming on the copper, witch would prevent them from soldering properly.

Not all parts were. " tinned" some were gold plated.... ect... Just though I would share the term used in industry.


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