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HDC1080: Protection of sensor during assembly

David Wright33
Intellectual 805 points
Part Number: HDC1080
Other Parts Discussed in Thread: HDC2021,

Hi There,

As per item 9.3.2 in the datasheet I would like to protect the sensor surface from any chemicals that they may come into contact with during their trasit out of the tape and through assembly of the PCB and the product, only to be come un-protected for testing and end usage. 

I have read over the Sotrage and Handling guidlines but found no reference as to how the sensor should be protected. In an ideal world I wouldhave hoped that a coating of Kapton Tape over the top of the sensor body (not touching the window) would be appropriate. But given the sensitivity of the device and the recommendation of the Storange and Handling guidlines (avoiding tape), I thought I would enquire as to the recommended scheme.

Can anyone provide a reccommendation for protecting this sensor?

Thanks,

David 

  • 0
    TI__Mastermind 28075 points

    Hi David,

    Whenever possible we recommend avoiding exposure to moisture (such as condensation or board washing), or exposure to chemicals (such as flux or those listed in the storage and handling guidelines you mentioned). Typically avoiding board washing and using a no clean solder paste are enough to prevent any issues from manufacturing. After that I would just ensure that any manufactured boards are stored properly, and you should be fine. 

    In the case a conformal coating is to be performed, then a Kapton tape can be used to protect the sensing element, but should be removed before the sensor is actually used. We also offer the HDC2021, which comes with a factory-installed protective tape cover. 

    Best Regards,
    Brandon Fisher

  • 0 in reply to Brandon Fisher94
    Intellectual 805 points

    Hi Brandon. 

    The product is to be used in a clean room environment so the board itself needs to be cleaned. I will look into assembling all of the other components, cleaning the PCB, and then assembling this single component with no-clean paste.

    If a kapton tape covering were to be used, is there a particular tape adhesive that should be used/avoided? The usual choices are silicone and arylic. 

    I waish I had seen the HDC2021 earlier! I would certainly have gone with a version that has the cover, unfortunately our design has the NC pins on the HDC1080 grounded, which will casue problems with that part's DRDY/INT pin.

    Thanks,

    David

  • 0 in reply to David Wright33
    TI__Mastermind 28075 points

    Hi David,

    David Wright33 said:
    The product is to be used in a clean room environment so the board itself needs to be cleaned. I will look into assembling all of the other components, cleaning the PCB, and then assembling this single component with no-clean paste.

    That method should work fine. 

    I have used a silicone adhesive Kapton tape in the past. I couldn't say whether or not an Acrylic tape would be better or worse, but I would say stick to silicone if that option is acceptable for you. 

    Best Regards,
    Brandon Fisher

  • 0 in reply to Brandon Fisher94
    Prodigy 10 points

    Hi Brandon -

    Any way to process using DI water wash? If we applied a protective boot (caplugs or similar) during wash, would that suffice for device protection?

    Is the main concern condensation? Or water jet impingement force? Both?

  • 0 in reply to Tyler Sventek
    TI__Mastermind 28075 points

    Hi Tyler, 

    The primary concern is liquid water (condensation or otherwise) directly on the sensing polymer. Having this sprayed with force directly onto the polymer would likely make the effects worse, but the main problem is still just the liquid water. 

    I can't say that we have experience with caplugs, but if it can be guaranteed that DI water won't make contact with the sensing polymer during wash you could get away with it. 

    Best Regards,
    Brandon Fisher