One thing that I dont think is pointed out clearly ( unless I missed it)
is that the P after the date stamp is identifying as from the mexico plant.
Thats a very good indicator of quality if that 'P' is there ( assuming it does actually mean mexico site)
It would be good to know more about the other codes, such as lot code, and the mystery XX idents ( in red below)
Methods mentions two things:
If methods can confirm he went to tijuana factory that would pretty much seal the "P" as indicating mexico site ( or was it via irtronix which isn't factory direct)Purchased direct from the factory
You can purchase the genuine fets in china also at good prices through irf china ( they get them supplied from mexico)
Another methods quote:
If that is true, then the 'P' is a very good indicator of quality.Turns out the TO-220 is ONLY built in Mexico - nowhere else
Interestingly I"ve been testing some batches of fets which are both from the "p' factory, both irf4310 type,
with identical markings except for the "xx" mystery ident, and they show different values from a simple resistance test across the drain and source.
I suspect that even with the same factory, that depending on which line the fets are made on there are differences in quality. Purely based on these 4310 fets.
More info on the assembly lot code and xx code might be useful