Sunday, 4 August 2019

pcb - Tips for identifying an unknown chip?


What tools and techniques can I use to identify an unknown IC with no markings?


Today I encountered a microcontroller under an epoxy blob. The blob had 11 pads on each of four sides, perhaps 44tqfp. From the board, I know which pin is the reset line and I probably know which pins make up an SPI interface.



Is there such a thing as an expert system for answering these puzzles with the information I have?


Are there any searchable databases of pinouts online?


Would X-raying/Decapping the package be worthwhile?



Answer



X-ray won't tell you much. Dimensions of the chip and where the bonds are attached. Decap is probably necessary. You should be able to get the manufacturer from text on the die, which will be a big clue. If you are really lucky, the manufacturer will put something on the die to help you ID the part number.


If you have a subscription to a tear-down company, you could scan their die photos and if you are luck find a match.


For a fee, a tear-down company will do this work for you and send you a full report on the part. Here's a list of a few such companies:



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