Electronics > Projects, Designs, and Technical Stuff

Is "integrated circuit burn-in" a thing?

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AndyC_772:
Hand soldering imposes far greater thermal stresses on components than a correct reflow profile.

I've wrecked several ST accelerometers this way. IIRC they were the first parts I ever had to learn to reflow using a preheater and hot air station, and once I'd figured out how to minimise the peak temperature they ever experienced, they worked fine.

Berni:
That is a very weird problem there.

I wouldn't really expect any failure in the MEMS structure to actually kill the SPI communication. I seen weird behavior of some MEMS IMUs due to a floating pin, funny enough the problem on that one only seamed to appear when it was at below freezing temperatures. I suppose some noise or bad decoupling could cause the internal CPU to rarely misstep and crash, or perhaps the timings,levels or rise times on some of its pins are capable of putting its internal logic into a weird meta stable state that eventually gets it to crash.

As for explaining the "burn in" period that can possibly be caused by soldering flux that was not properly cleaned from the board. It very slowly absorbs moisture from the air, causing its conductivity to drift and making for seemingly time related behavior. Tho these resistances tend to be so high that it takes a floating pin as mentioned above to detect it. It usually takes a very heavy layer of flux and lots of moisture for it to become conductive enough to mess up an actively driven digital signal (But i seen it happen).

We also found that ultrasonic cleaners have the ability to kill MEMS devices and barometers

floobydust:
What kind of flux, pcb wash and dry are you doing? That can cause problems with moisture ingress and your "burn-in" is just waiting for things to dry out.
The reflow profile has to be decent, not sloppy with too much heat or too long. Excessive PCB flex during handling can also cause shifts.

Best to be careful and use scientific method (change only one thing at a time) to troubleshoot your problem.
Encountering hassles now is much better than when in production...

IDEngineer:

--- Quote from: SilverSolder on April 25, 2019, 05:33:16 pm ---Could it be that you were just unlucky, and if you bought some more parts they would behave better?
--- End quote ---
Maybe... but how many more before they're "trustworthy"? If I have 50 bad parts now, and 50 more all work great, that's a 50% reliability rate. I wouldn't design with a part that is only 50% reliable.

jmelson:

--- Quote from: AndyC_772 on April 25, 2019, 07:57:21 pm ---Hand soldering imposes far greater thermal stresses on components than a correct reflow profile.

I've wrecked several ST accelerometers this way. IIRC they were the first parts I ever had to learn to reflow using a preheater and hot air station, and once I'd figured out how to minimise the peak temperature they ever experienced, they worked fine.

--- End quote ---
Maybe, maybe not!  Yes, what you say is possible.  But, if you solder one pin at a time, for just a second or so, the BODY of the part never gets heated more than 10 C above ambient.  When reflowing, the whole component is heated to 200C+ above ambient.  Maybe this part is really sensitive to that internal temperature.

OK, you say you had to use a hot air station, that concentrates the heat on the LEADS, not the component body.  That's what I'm talking about.  My guess is the OP's contract assembler used ordinary reflow, heating EVERYTHING to 250 C for a minute or more.

Jon

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