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What's inside the cheapest and fakest jellybean opamps

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magic:
That's a question I asked a few months ago after getting some fake opamps myself and seeing countless reports of even the most mundane ICs being counterfeited.

Courtesy of AliExpress and their coupons I obtained a number of too cheap to be true opamps for virtually nothing straight from the source :D For a good measure I also bought samples from local resellers whenever I saw suspiciously looking chips at a place I was buying anything else from. Sure enough, wherever you get them from, it's all the same junk.

I wondered whether to test them or tear them down. Since a few types I had in quantities of 10, I decided to take the "don't turn it on" route with those. What I found inside quickly convinced me that testing will be utterly boring and instant teardown is the way to go.

Now a short description of the specimens and some pr0n. Image quality isn't quite Zeptobars level but good enough for identification ::)

NE5532
I got a few to see if anything has changed since Zeptobars photographed one. Some turned out to be the same, but one was different.
Dice: 3, 659.

NE5534
As far as I know, there are no fully pin-compatible substitutes for this IC. So I wondered what could they put inside? Maybe there is a Chinese implementation of this classic design? Well, maybe not. They just don't care.
Dice: 8, ANON.

LM833
Another common audio opamp. Same as one of the 5532s, but bottom of the packages is different. The die looks quite funny, like a cartoon drawing.
Die: 659.

NJM4558
This one is popular with guitarists for whatever reason. Can we get the genuine JRC sound from AliExpress?
I actually had two, but destroyed the other one before taking the pic. It looked much more legit than this one, only the lettering was laser etched rather than printed.
Dice: 3, 46334.

TL082
Many cases reported of these behaving like LM358. What could be the reason?
Die: GI

TL071
What might be inside a single version of the above? More of the same, of course.
Die: 8, 20GI

LM358
If TL082 is LM358 than what is LM358?
Die: ADI6

UA741
Surely no one is going to fake the old 741, right?
Die: 20GI

OP07
This chip I actually bought long ago expecting to get a real one. Oh well.
Die: GI956

All in all, there isn't much rhyme or reason to it. Same part may have different dice, same die may be found in different parts, even BJT and JFET at the same time. Single opamps are realized by connecting one half of a dual die. As far as I can see, all dice implement LM358 or RC4558 topology. I will leave it as an exercise for the reader to figure out which are which :P

It could perhaps be interesting to test whether they meet the spec of LM358/RC4458, and they probably do. I suspect these are off-the-shelf products that fraudsters order without markings or as bare dice and print whatever BS on them. At scale it's probably cheaper than grinding markings off of recycled chips.

Prehistoricman:
GI and 20GI are interesting. They look like they could have the same netlist, just laid out slightly differently.

What's with all the round vias in these chips? I thought that they were always square.

amyk:
956 and 659 feel too close to be a coincidence... does anyone recognise the logo in the middle of GI956?

schmitt trigger:
My theory is that counterfeiters will package whatever surplus or rejected dice they can source, and then label the plastic package with whatever part number remotely resembles the function.

After all, an opamp is an opamp, right ?  :scared:

magic:

--- Quote from: Prehistoricman on March 10, 2020, 01:46:52 am ---GI and 20GI are interesting. They look like they could have the same netlist, just laid out slightly differently.

--- End quote ---
:-+
As far as the signal path is concerned, all LM358 here implement the attached circuit.
This is from Fairchild LM358 datasheet, the one they bought from Samsung.


--- Quote from: Prehistoricman on March 10, 2020, 01:46:52 am ---What's with all the round vias in these chips? I thought that they were always square.

--- End quote ---
You probably mean lateral PNP transistors ;)
They can be any shape, though round is optimal because it provides uniform base width in all directions.

There are no vias here and the closest thing are "contact windows" - holes etched is the insulation layer between silicon and metal, permitting a connection. The location of those is clearly visible on ADI6, because metal appears brighter in those areas for some reason.

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