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harshamahadevaiah
harshamahadevaiah
Associate
January 13, 2015
Question

Storage Temperature of STM32F103RGT7

  • January 13, 2015
  • 2 replies
  • 734 views
Posted on January 13, 2015 at 22:01

Hello,

I am currently using STM32F103RGT7 to control my BLDC motors. I am suppose to sterilize the PCB which has the controller mounted on it in an Autoclave (steam sterilization). During which the controller will be subjected to temperature close to 140 degree centigrade for 5 to 10 minutes.

The controller is not powered during this period, I would like to know if the the controller can withstand this temperature for the mentioned time duration. Are there any chances of the memory(flash) being affected?

Regards,

Harsha.M
    This topic has been closed for replies.

    2 replies

    waclawek.jan
    waclawek.jan
    Super User
    January 14, 2015
    Posted on January 14, 2015 at 08:31

    According to datasheet, table Thermal characteristics, Storage temperature range, it may go up to 150 deg.C. However, this does not include impact on FLASH. Elevated temperature undoubtedly reduces retention - charge leakage from the floating gate increases exponentially with temperature, unfortunately the exponent and its variations are process dependent, so it's almost impossible to say anything binding without the assistance of the manufacturer.

    A rough estimate can be made from the datasheet data, though: retention at 85 deg.C is 30 years, and at 105 deg.C is 10 years, i.e. a 3x decrease in retention for cca 20% increase of temperature; thus further 20+20% increase in temperature should result in 3x 3x = 9x decrease in retention, resulting in roughly 1 year. OTOH, you are not going to keep it in autoclave all the time; if it's there say 10% of time and the rest of the time it is at say up to 50 deg.C (which is roughly the operation temperature of the chip at room temperature, dependent of course on the clock frequency, power supply etc.) where temperature impact on retention is negligible, IMO it should be quite safe to say the data in FLASH are OK for a couple of years, maybe up to 10.

    Still bear in mind, that there might be more complex failure mechanisms ahead, so again, nothing definitive can be said without the manufacturer's comment.

    JW

    harshamahadevaiah
    harshamahadevaiahAuthor
    Associate
    January 27, 2015
    Posted on January 27, 2015 at 21:58

    Thank you for this useful information.

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