| General > General Technical Chat |
| Did I buy fake Linear Tech. ICs? |
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| qat:
Got a couple of LT3797s from Aliexpress since they're more or less impossible to get anywhere else. Since I pretty much expected to get fake or non-working ones I ordered from two sellers and got two sets of different looking ICs. (see images) One set has a white text printed on them in poor quality and the other has laser engraved text on it. The underside is also a little different, one looks to have pads with marks from testing pins and the other has slightly scrached pads (maybe they've spent some time in PnP reject-bucket?). Are LT's chips just different sometimes or did I receive dodgy ones? The chips in general have a unique package so I don't see why anyone would put down the effort to fake these over some unobtanium STM32 which would surely be more profitable. If anyone can provide some insight it would be super helpful! Thanks |
| Algoma:
The date codes are quite different, likely reclaimed chips that have been refurbished (sanded?) and tested. |
| qat:
That’s a very probable explanation, it does looks one of them has some sort of grinding marks. Maybe I’ll have a go with a micrometer gauge and see if there’s a difference. The PCB they’re going on has two of them so maybe I’ll mount one of each and hope I potentially only need to replace one. :-) |
| magic:
The printed ones have date codes all over the place, mostly from early 2010s, they are recycled chips in unknown condition, mostly functional. The lasered ones have identical, fairly recent date code and won't work, may give out magic smoke. So says the crystal ball :-// One thing I don't understand, which one has the scratches on the bottom and which looks like it was sanded? |
| T3sl4co1l:
Interesting that the one looks sanded, but the plating looks fine, aside from some probe marks? The other looks virgin, aside from some scratching. Or maybe it was hit with an orbital sander, I don't know... The marking is interesting... offhand, I have one chip (an SSOP-20 or so) that is painted white, solid with no defects. I also have a uModule with larger printing but does show similar voids in the fill. Seems like, for a small QFN, the marking should be solid, that the voiding only occurs in wider fills or something. Not sure offhand if they ever laser mark them, but it sure seems like they would do a better job of it than that. Tim |
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