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HDC2021: About reflow without polyimide tape

Y.Ottey
Mastermind 6145 points
Part Number: HDC2021

Dear all,

Some of our customers would like to consider the HDC2021.

Please tell me about reflow without the polyimide tape attached.

When checking the HDC2021 data sheet, the following was found.

I would like to ask the following questions regarding the above contents.
1. Is the following recognition correct from the above description?
・If polyimide tape is not attached, reflow can be performed only once (possible twice if conditions are met).
・If polyimide tape is attached, reflow can be performed up to 3 times.

2. I have a question about the highlighted part of the above description.
The above describes the case of removing the polyimide tape. What kind of cases are you supposed to remove the polyimide tape?

Best Regards,

Y.Ottey

  • 0
    TI__Mastermind 28075 points

    Hi Y.Ottey,

    Thank you for your post. 

    Y.Ottey said:
    I would like to ask the following questions regarding the above contents.
    1. Is the following recognition correct from the above description?
    ・If polyimide tape is not attached, reflow can be performed only once (possible twice if conditions are met).

    Correct. I should note that without the tape both the first and second reflows must follow the listed guidelines. Exposing the sensing polymer to any contamination or to liquids (such as during board wash) can cause errors in reading.

    Y.Ottey said:
    ・If polyimide tape is attached, reflow can be performed up to 3 times.

    Yes, please ensure the guidelines in the Soldering Reflow section are still followed. 

    Y.Ottey said:
    2. I have a question about the highlighted part of the above description.
    The above describes the case of removing the polyimide tape. What kind of cases are you supposed to remove the polyimide tape?

    The polyimide tape is only intended to be left on during production and possibly storage. It should be removed during sensor operation for best results. 

    Please let me know if you have any additional questions.

    Best Regards,
    Brandon Fisher

  • 0 in reply to Brandon Fisher94
    Mastermind 6145 points

    Dear Fisher,

    Thank you for your reply.

    I would like to ask adding question about the following sentence.

    "The polyimide tape is only intended to be left on during production and possibly storage. It should be removed during sensor operation for best results."

    Does the meaning of the above description mean that it is necessary to remove the polyimide tape in order to obtain the electrical characteristics of the data sheet?

    Or does it mean that by removing The polyimide tape, better performance can be obtained than that stated in the data sheet?

    Regards,

    Y.Ottey

     

  • 0 in reply to Y.Ottey
    TI__Mastermind 28075 points

    Hi Y.Ottey,

    The tape must be removed for accurate measurement of relative humidity. Section 8.3.1 of the datasheet confirms this. 

    Best Regards,
    Brandon Fisher