Questionable STM32F427

[Joe.H]

Last year I had a production run (built in China) of a board that uses a STM32F427 - 100 pin.

This last spring I had another production order built (Feb to May) and the behavior of the part seems to be having timing related issues - same firmware.

I took pictures of the part and there appears to be a difference in marking enough that I would like to ask the experts if this NEW part is really from ST or is it a knock-off.

This is the part from last year which has proper timing response.

Notice the eject pin mark in upper right corner and the circle e4 between the ST and ARM

This is the Questionable part - timing issues.

Notice no eject mark and its a e3 between ST and ARM as opposed to e4. There is also a OD marking in lower right corner and over-all the part marking in general is formatted differently.

Also - the questionable part has no Revision Identifier -- across from VGT6 as the good part is showing revision B.

What does the e3 or e4 stand for?

Is the second picture one of a REAL ST part.

Thanks for any help -- my recently received boards are all showing timing issue.

[waclawek.jan]

> What does the e3 or e4 stand for?

Pb-free finish categories
 
JEDEC J-STD-609 Pb-free finish categories describing the lead-free (Pb-free) terminal finish/material of components and/or the solder paste/solder used in board assembly are:
 
    e0 - contains intentionally added lead (Pb)
    e1 - tin-silver-copper (SnAgCu) with silver content greater than 1.5% and no other intentionally added elements
    e2- tin (Sn) alloys with no bismuth (Bi) nor zinc (Zn), excluding tin-silver-copper (SnAgCu) alloys in e1 and e8
    e3 - tin (Sn)
    e4 - precious metal (e.g., silver (Ag), gold (Au), nickel-palladium (NiPd), nickel-palladium-gold (NiPdAu) (no tin (Sn))
    e5 - tin-zinc (SnZn), tin-zinc-other (SnZnX) (all other alloys containing tin (Sn) and zinc (Zn) and not containing bismuth (Bi))
    e6 - contains bismuth (Bi)
    e7 - low temperature solder (≤ 150 ºC) containing indium (In) [no bismuth (Bi)]
    e8 - tin-silver-copper (SnAgCu) with silver content less than or equal to 1.5%, with or without intentionally added alloying elements. This category does not include any alloys described by e1 and e2 or containing bismuth or zinc in any quantity.
    e9 - symbol - unassigned

ST uses several different packaging contractors, they may have different molds/ejector marks, and slightly different way to mark the parts. Marking also evolves in time, as ST finds they need more identification for tracking etc.

There are also several revisions of the chip - see errata. Chips themselves used to be manufactured at several sites (this all is identified by the revision letter, again see errata and the chip ID); they should be functionally identical though.

Note, that this is a primarily user-driven forum with casual ST presence, so you might want to ask ST directly, through web support form or FAE.

You may want to discuss the timing issue here, perhaps starting a new thread.

JW

[Tesla DeLorean]

These parts were packaged in two different countries, so likely different processes and tool/die

For functional differences, better to check the Device ID and chip stepping (DBGMCU DEVID)