To ensure proper handling during assembly, follow the detailed guidelines in the device datasheet and silicon user’s guide. Key recommendations include:

• Assembly Sequence

  • Mount the RH sensor as the final step in the assembly process.

• Reflow Soldering:

  • Always follow the IPC/JEDEC J-STD-020 standard profile with peak temperatures at 260°C.

  • Limit to one reflow pass and avoid rework.

• A-B-A Swap Exception:

  • If rework is necessary (e.g., for diagnostic purposes), follow these precautions:

    • Minimize handling.

    • Use a heat gun to remove the sensor cleanly, without additional flux.

    • Perform rehydration post-removal, as the sensor may have been exposed to drying heat.

• Solder Paste and Cleaning:

  • Use no-clean solder paste. Do not clean boards post-assembly.

  • If cleaning is necessary, use distilled water only.

  • Verify that all materials used are free of harmful chemicals (consult MSDS documentation).

  • Example: Kester R276 is a recommended no-clean solder paste shown to be compatible with TI RH sensors.

• Chemical Exposure Avoidance:

  • Avoid materials that emit VOCs during baking or curing.

  • Examples of contaminants include: PCB wash chemicals, adhesives, epoxies, some conformal coatings, and outgassing byproducts.

• UV Light Avoidance:

  • Avoid exposing the RH sensor to UV light. UV light can damage the sensing polymer and introduce irreversible RH errors.

• Mechanical Protection:

  • Do not subject the sensor to high-pressure air blasts or ultrasonic cleaning.

  • Use low-pressure, oil-free dusting if needed.

• Conformal Coating:

  • Must not be applied directly on the sensor cavity, doing so will prevent ambient RH measurements

    • Ensure the cavity is protected during curing. Make sure to choose an conformal coating that does not outgas during or after curing to reduce the risk of gaseous chemical contamination of the RH sensor.