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Humidity-related output shift on ADXL343 during tilt detection

Thread Summary

The user observed a persistent shift in the Z-axis output of the ADXL343 when exposed to high humidity, which was only resolved after thermal exposure at 60°C. The issue is suspected to be due to moisture absorption in the plastic package, altering the mechanical force profile on the sensing die. A coating material can help insulate the part, and the ADXL355/7B with a hermetic ceramic package is recommended for better humidity resistance.
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Category: Hardware
Product Number: ADXL343

I am using the ADXL343 for a simple tilt detection application.

This is a threshold-based tilt detection.
The Z-axis output measured at 80° is stored as a reference, and the current Z-axis value is compared against it during operation.

When the device was operated in a high-humidity environment, a significant shift in the Z-axis output was observed.
As a result, tilt was detected at angles lower than expected(e.g., around 75°).

After returning the device to a low-humidity environment, the output shift remained.
However, after leaving the device overnight at approximately 60 °C, the output behavior recovered and tilt detection again occurred around 80°.

This behavior suggests that exposure to high humidity caused a persistent change affecting the Z-axis output, which remained even after humidity was reduced and was only resolved after thermal exposure.

If anyone has insight into physical or electrical mechanisms that could explain such humidity-related output shifts in the ADXL343—whether related to the sensor itself, packaging, or external conditions—I would appreciate your thoughts or experience.

Parents
  • Hello   thanks for posting!

    MEMS are inherently sensitive to any kind of package deformation and based on customer feedback and subsequent DOEs, we suspect that the package absorbs the moisture, in a way that changes the mechanical force profile on the sensing die, which leads to shifts in position/orientation of the sensing elements.

    Unless otherwise noted, our parts with plastic package are not designed to operate in condensing/humidity conditions. Using a coating material to insulate the part could help. (this could also translate in different offset shift if there is any sensible temperature drift)

    If size and price is not a main boundary ADXL355/7B feature a hermetic ceramic package which would help with these repeatability issues.

    hope this helps, let me know how can I further assist you,

    Mario SM

Reply
  • Hello   thanks for posting!

    MEMS are inherently sensitive to any kind of package deformation and based on customer feedback and subsequent DOEs, we suspect that the package absorbs the moisture, in a way that changes the mechanical force profile on the sensing die, which leads to shifts in position/orientation of the sensing elements.

    Unless otherwise noted, our parts with plastic package are not designed to operate in condensing/humidity conditions. Using a coating material to insulate the part could help. (this could also translate in different offset shift if there is any sensible temperature drift)

    If size and price is not a main boundary ADXL355/7B feature a hermetic ceramic package which would help with these repeatability issues.

    hope this helps, let me know how can I further assist you,

    Mario SM

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