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040 Fakes and Identification

Posted by: jessenator on 2022-01-30 11:23:25

Figured I'd break this out earlier, rather than later. Let's put fake detection methodology, etc in this thread.

I'm going to pop in info from the thermals/L88M proofing thread into here, but feel free to add anything I've left out.

@Bolle let me know if you have other info on fakes and such similar to this (for some reason mobile won't let me copy the quote like I did below...):
Check the other numbers in the lower left corner. As far as my data collection goes those do give away the mask as well. As far as I can tell it's like this:
D98D ends with -010
E31F ends with -001
E42K ends with -101
K63H have seen w/ both -104 & -103 L88M ends with -104

I'll add the mask tables that we have currently in a separate post

The date table might be in weeks for some and not for others, so IDK what's going on there, but here are the tables from the Polish site

FULL 040s:

Mask Process (μm) Fab Production years (if known) yy/wk?
D43B 0.8 MOS8 91/03-91/15
D50D 0.8 MOS8 91/50
D98D 0.8 MOS8 92/09-92/3-50
E31F 0.65 MOS11 93 - 2-Jun-95
E26A 0.65 MOS8 (???) 92-95
E42K 0.65 MOS11 2-Jun-95 - 13-Aug-00
K63H 0.57 TSC8 13-Aug-00 - 23-Nov-02
L88M 0.57 MOS11 Nov 23, 2002 - 2004 (?)

EC and LC 040s

Mask Process (μm) Fab Years of production if known
D39H 0.8 MOS8 92
E23G 0.65 MOS11 9339 - 02-Jun-95
E71M 0.65 MOS11 02-Jun-95 - 17-Jan-00
J46X 0.57 TSC8 17-Jan-00 - 07-Sep-2002
L89M 0.57 MOS11 From 07-Sep-2002

To me, the die looks bigger in this image. So this seems like one way to determine what version the chip is.

I'll do a proper overlay with a higher resolution, but here's from my phone for now:

So far, it looks like the L88M LRC is indeed smaller, but truth will out. I won't call it just yet, but it's a great theory to keep proving.

Posted by: jessenator on 2022-01-30 12:03:41

One thing I'd also like to get some clarity on is what's involved in detecting and revealing fake printing on the ceramic.

Is this done with acetone? Something stronger?

Does the true printing not dissolve with acetone?

It might be good to get close-ups of the markings that are genuine vs known fakes (obvious misprints, lacking FPUs, etc. functionality that's indicated)
I'll find the whole scans of this

Posted by: jessenator on 2022-01-30 12:15:27

quite large image linked on thumbnail

Posted by: jessenator on 2022-01-30 13:38:59

I'll do a proper overlay with a higher resolution, but here's from my phone for now:

Safe to say the die is shrinking (with my samples anyway)

(worth reminding that the E31F and E42K have the same size of die (.65um))

Posted by: jessenator on 2022-01-31 07:52:48

Just so it's not in a collapsed quote, here's the mask rev chart:

FULL 040s:

Mask	Process (μm)	Fab	Production years (if known) yy/wk?
D43B	0.8	MOS8	91/03-91/15
D50D	0.8	MOS8	91/50
D98D	0.8	MOS8	92/09-92/3-50
E31F	0.65	MOS11	93 - 2-Jun-95
E26A	0.65	MOS8 (???)	92-95
E42K	0.65	MOS11	2-Jun-95 - 13-Aug-00
K63H	0.57	TSC8	13-Aug-00 - 23-Nov-02
L88M	0.57	MOS11	Nov 23, 2002 - 2004 (?)

EC and LC 040s

Mask	Process (μm)	Fab	Years of production if known
D39H	0.8	MOS8	92
E23G	0.65	MOS11	9339 - 02-Jun-95
E71M	0.65	MOS11	02-Jun-95 - 17-Jan-00
J46X	0.57	TSC8	17-Jan-00 - 07-Sep-2002
L89M	0.57	MOS11	From 07-Sep-2002

Found another eBay listing advertising MC-qualified 040s (at multiple speed ratings) with a mask rev of "G23E" [spoonerism of the E23G] with a left-side index number of "010" corresponding to the DXXX mask revision chips. Not linking to it, just be aware. It's quite similar to this story from another member—there's was a 25MHz-rated chip, but the other markings and quality of the printing is near-identical: https://68kmla.org/bb/index.php?threads/counterfeit-68040-l88m-mask-revision-from-ebay.36759/