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HDC3020: Abnormal data when high temperature and high humidity cycle test

Amber Si
Intellectual 2165 points
Part Number: HDC3020

Tool/software:

Hi team,

When customer use HDC3020 for high temperature and high humidity cycle test, they get below abnormal data: T=65491 (the mean of -45C) ,H=0

What test condition they execute is from T=66C, H=90 to T=25, H=30, round and round. When Temperature goes from 25C to 66C, data we test will report fault T=65491 (the mean of -45C) ,H=0 firstly, then we sent command a second time, we can get correct data(T=66,H=90)

What cause the fault data? how can we avoid this?

BR

Amber

  • 0
    TI__Genius 12215 points

    Amber,

    How many devices are being tested, and is this the only part that experiences this issue? Is the issue repeatable on this specific device? If so, does it consistently fail after a certain number of hours of this temp/RH cycling? My initial thought is that condensation may be forming either on the device or causing a short somewhere on the I2C lines. When moving from high temp & high RH (66C & 90% RH), to a lower temp, that will cause condensation. As temperature increases, the air can hold more moisture. Hence, if RH = 100% meaning full saturation at a lower temp, if temp is increased but the amount of water in the air does not change then RH will drop, because the air will no longer be at saturation. In this, when dropping from high temp and high humidity to low temp and low humidity, the customer may be dropping the temperature below the dew point, causing condensation since the colder air cant hold all that water vapor. They are dropping the RH, but it may not happen quickly enough.

    Please have the customer answer the questions, and investigate condensation on their PCB or the sensor as the likely cause.

    Regards

    -Alex Thompson

  • 0 in reply to Alex Thompson
    TI__Intellectual 2165 points

    Hi Alex,

    After check with customer, they have 10pcs HDC3020 tested at same time, and 3pcs can repeat this issue. I detailed the whole process of the test for better understanding the issue:

    1. The temperature and humidity chamber is adjusted to -5℃ in half an hour.
    2. -5℃ for 2 Hours.
    3. Adjust to 0℃ in 30 minutes.
    4. 0℃ for 2 Hours.
    5. Adjust to 5℃ & 90% RH in 30 minutes.
    6. 5℃ & 90% RH for 2 Hours.
    7. Adjust to 10℃ & 60% RH in 30 minutes.
    8. 10℃ & 60% RH for 2 hours.
    9. Adjust to 15℃ & 30% RH in 30 minutes.
    10. 15℃ & 30% RH for 2 hours.
    11. Adjust to 20℃ & 10% RH in 30 minutes.
    12. 20℃ & 10% RH for 2 hours.
    13. Adjust to 25℃ & 25% RH in 30 minutes.
    14. 25℃ & 25% RH for 2 hours.
    15. Adjust to 30℃ & 35% RH in 30 minutes.
    16. 30℃ & 35% RH for 2 hours.
    17. Adjust to 35℃ & 50% RH in 30 minutes.
    18. 35℃ & 50% RH for 2 hours.
    19. Adjust to 40℃ & 70% RH in 30 minutes.
    20. 40℃ & 70% RH for 2 hours.
    21. Adjust to 45℃ & 85% RH in 30 minutes.
    22. 45℃ & 85% RH for 2 hours.
    23. Adjust to 50℃ & 95% RH in 30 minutes.
    24. 50℃ & 95% RH for 2 hours.(Actual temperature inside box：66℃ ， actual humidity：95%RH)---Abnormal data appear 
    25. Adjust to 25℃ & 30% RH

    I query If as you said it is caused by condensation, the abnormal data must appear when moving from high temp & high RH to a lower temp(that means we can get fault data at step25 above), but unfortunately, 3pcs failure are all appear during high temp & high RH.

    What other cause?

    BR

    Amber

  • 0 in reply to Amber Si
    TI__Genius 12215 points

    Amber

    Thank you for the detailed test description. Given that high RH, condensation could still form if the humidity is moving at reaches 100%.

    Is water soluble flux being used, and not being cleaned off? I have seen shorts caused at high humidity even without condensation when water soluble flux is used and not cleaned off.

    Do these 3 parts repeat the issue consistently, and the other 7 never have the issue? Are there any intermittent failures?

    Regards

    -Alex Thompson

  • 0 in reply to Alex Thompson
    TI__Intellectual 2165 points

    Hi Alex,

    For efficient discussion. Let's have a quickly call through webex meeting, I'll sent you calendar soon.

    VR

    Amber

  • 0 in reply to Amber Si
    TI__Genius 12215 points

    Amber,

    I have accepted your meeting invite, I'm looking forward to speaking with you then.

    Regards

    -Alex Thompson