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HDC2022: about PTFE filter and heater

ACGUY
Guru 11170 points
Part Number: HDC2022

Hello E2E,

I have two questions.

1
The HDC2022 has PTFE filter on top surface. I understood from datasheet this filter protect for humidity detection element from water, particles less than 100nm and dirt due to chemicals during soldering.
If flux adheres to the PTFE filter, does the device allow the flux to be removed with alcohol?

2
This device has an integrated heater.
Does this device management or control the temperature of the heater?
Is this heater effective in the dehumidification process?

Regards,
ACGUY

  • 0
    TI__Expert 3270 points

    Hi ACGUY,

    You can use a no-clean flux or a VOC free flux while handling the HDC2022. Alcohol may cause some drift so it should be avoided, but the device can be cleaned with distilled water. You can also cover the sensor with a polyimide tape or kapton tape and can clean the sensor with alcohol. 

    The device heater can be used to remove any condensation on the part. There is no way to control the heater temperature, and in certain layouts, the heater temperature can go up to a 100°C 

    Regards,
    Pavani Tenneti

  • 0 in reply to Pavani Deepthi Tenneti
    Guru 11170 points

    Hi Pavani,
    Thank you for your reply. Can I have question more?

    >> the device can be cleaned with distilled water.

    Q) Does TI recommend using distilled water to clean the soldered board?

    >> You can also cover the sensor with a polyimide tape or kapton tape and can clean the sensor with alcohol.

    Q) To protect the device with polyimide tape, 1: unpack the tape before soldering, 2: put the cut polyimide tape on all ICs, 3: rebake in the oven, 4: put it back in the tape packaging again, Four steps are required.
    Does TI recommend performing those tasks?

    Please let me know about the application.

    Q) I understand that the temperature rise of the device due to the heater depends on the material of the board. Is there a repatriation document regarding device temperature, board material and heater uptime?

    Q) Customers are planning to incorporate this device into agricultural IoT devices. The place is in a vinyl house. Humidity is expected to exceed 90%, so a dehumidifying process is required on regularly for proper humidity sensing.
    I think this device is not matched for this application, please let me know TI's opinion.

    Best regards,
    ACGUY

  • 0 in reply to ACGUY
    TI__Expert 3270 points

    Hi ACGUY,

    • You should only clean the sensor with distilled water if the device was exposed to any contaminants or if it has some residue on the device. If the part is washed with distilled water, please follow the bake and rehydration process. 
    • The HDC must be added in the last assembly step. In case the PCB passes through multiple solder cycles (as is the case for PCBs that have components on the top and bottom side), adding the HDC last reduces the risk of damage to the sensing polymer from contaminants or excessive heat. In case you are using a kapton cover, place the cover over the sensor opening during manufacturing and assembly process. You can remove the cover when the device is ready to measure environment temperature and humidity. 
    • You can refer to this document  for placement guidelines. The heater can be left on until the device condensation evaporates.
    • Recommended humidity operating range is 20% to 80% RH (non-condensing) over 0°C to 60°C. Prolonged operation beyond these ranges may result in a shift of sensor reading, with slow recovery time. The heater can help dehumidify the environment around the sensor occasionally, but exposure to high humidity can damage the sensor. 

    Regards,
    Pavani Tenneti