Substituting Power MOSFETS, buying from AliExpress, obsolete parts

[wraper]

IC on the bottom appear to have sanded surface (porous surface + sharp edges). Thus I strongly suggest rubbing it with solvent to see if you can wipe blacktopping. Presence of key is very suspect. National semi logo looks wrong.

[Phil1977]

You are right that the "inked" marking on the part "B" seems suspicious.

But electronically I can't measure any difference between both parts.

Slew rate is 1.75V/us for part A, 1.81V/us for part B. Datasheet value is 1.1V/us typical, but with somehow different test conditions.
Short circuit current is 26mA for 5V supply voltage for both parts. Datasheet value is 22mA typical.

I can not proof that it is genuinely from National semi. But it performs quite well.

PS: The part with the laser marking is the one from the reputable supplier.

[wraper]

What about current consumption? Should be about 800uA.

[Phil1977]

593uA for the AliExpress one
580uA for the Digikey one

As already said, please never trust semiconductors from AliExpress. A fake-ratio of 25% or more is bad enough - but not all parts from the grey market are automatically bad.

[wraper]

Maybe you got lucky and got relabeled salvaged original e-waste parts.

[Phil1977]

I don't think it´s from e-waste if you get 25 more or less identical parts that have no solder residues and have that absolutely typical pin angle that prevents them from fitting into sockets, PCBs or breadboards 

Someone must have had a big surplus of these ICs. It´s also highly unplausible that someone does so much effort to fake 25 packages for only €3.- Wages in China aren't that low any more for a long time.

I´m quite sure we both can't explain all that´s happening in global trade.

[wraper]

I don't think it´s from e-waste if you get 25 more or less identical parts that have no solder residues and have that absolutely typical pin angle that prevents them from fitting into sockets, PCBs or breadboards 

Someone must have had a big surplus of these ICs. It´s also highly unplausible that someone does so much effort to fake 25 packages for only €3.- Wages in China aren't that low any more for a long time.

I´m quite sure we both can't explain all that´s happening in global trade.

I see this argument all the time and it does not add up with reality, even wage part. Many rural areas in China still are extremely poor and people are desperate to get out of there (which is not easy). Even <10 cent components get counterfeited all the time. As of solder residues, counterfeiters found ways to remove them. I've even seen salvaged QFN and similar packages made to look like never soldered but with large part of them electrically shorted or faulty in different ways (beside altered marking). The fact is that IC was sanded and relabeled. There must have been a reason for that. If the part is actually original inside, then it's most likely because they had a bunch of salvaged parts with different date code marking, worse or random grade.
Do you think they are sorting components for no reason:

[thm_w]

Its possible they were re-labelled just to give them a newer date code, but I can't decipher what year 'R' is 2018? Or is it 3 for 2013 or 2023? Anyway, its definitely more likely they are salvaged cleaned up parts as you say. They have tools to straighten the leads, clean off the solder, replate pins, etc.

Which is ok for hobby purposes if you have the time to kill and analyze them.
But not something I'd recommend at all if you are starting out and don't have the knowledge.

Its not as common on aliexpress last time I looked but on taobao you can easily find sellers that will sell you salvaged ICs directly and honestly. They leave them as-is, no remarking.

[BrokenYugo]

The one time I got what I'm fairly certain was genuine new/NOS western branded silicon direct from China on Ali/ebay it was a whole 10 tube of EPROMs. When I went back for more the store/seller had disappeared. So yeah, low odds.

[wraper]

The one time I got what I'm fairly certain was genuine new/NOS western branded silicon direct from China on Ali/ebay it was a whole 10 tube of EPROMs. When I went back for more the store/seller had disappeared. So yeah, low odds.

From what I've seen most of 27xx(x) EPROMs are relabeled with newer date code and likely better speed grade. I once ordered ST M2732A and reordered more a few weeks later.  Both batches had exactly the same impossibly fresh date code. However one batch actually was early 25V prg 2732 from AMD. Another had a correct ST 21V die inside, of course speed grade couldn't be verified to be true. Similar to the picture below. I doubt there is some never ending NOS EPROM supply, most likely they are erased pulls from disposed equipment.