Electronics > Manufacturing & Assembly

Dull finish on new Texas Instruments PDIP parts. Is this normal?

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I only buy parts from Mouser and Digi-Key and have observed for the past few years all Texas Instruments PDIP parts (e.g. 74HCT series) have sort of a dull finish on the pins. If I scratch it with metal it's shiny underneath, so I guess it's some kind of oxide layer.

The parts I buy all work fine though I use dual wipe sockets and don't solder them to the board. I've dug out some old projects from years back and the oxidation (if that's what it is) looks no different than how it looks on the new parts. So whatever it is, it isn't getting worse with time. The old projects still work fine too.

In comparison PDIP packages from any other vendor (NXP, OnSemi, etc.) purchased from Mouser/Digi-Key don't look like this. It's only Texas Instruments.

I'm tempted to say it's not a big deal, but I still don't know what I'm dealing with. Any ideas? Do they just use a different metal for the pins compared to other manufacturers?

I have seen it too. It is weird. Do not know what it is but just in case i use the eraser to clean the pins before soldering.

How many years have you been noticing that? I have several 2012 through 2017 PDIPs from them and they are still shiny.

Some part number options are (SN | NIPDAU) (some even NIPDAUAG) - not sure if this could be it...

Otherwise matte tin is good vs bright tin  (tin whisker mitigation) ? There was a big push to get away from any "shiny tin" finishes on parts due to this....

Pics? I thought that matte appearance was something to do with the manufacturing or plating process of the leads on DIP ICs, power transistors, etc. Seems more common than not.


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