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HDC2080: Assembly Handling

Abigail Leonardi
Expert 3410 points
Part Number: HDC2080
Other Parts Discussed in Thread: HDC3021, HDC2021

Tool/software:

Hi,

One of my customers is looking for guidance as they understand that this device cannot be exposed to most of the chemicals used during the PCB washing process and that adhesives or tapes should not be applied directly to the sensor. With that in mind, we were wondering if there is an available option (or perhaps an alternative part with the same layout) with a removable protective cover that could shield the sensor during cleaning.

Ideally, they are looking for a solution that would allow us to protect the sensor throughout assembly and then safely remove the cover before operation without risking damage. Does the team have any recommendation on this? Thank you!

  • +1
    TI__Expert 3385 points

    Hi Abigail, 

    Yes, I would direct your customer to HDC2021 or HDC3021. They come with a removable polyimide tape cover. The tape cover provides protection against pollutants that can appear in certain stages of the manufacturing process, such as SMT assembly, PCB board wash, and conformal coating. After assembly, the tape cover can be removed and the sensor is used normally.

    Best,

    Sakeenah 

  • 0 in reply to Sakeenah Khan
    TI__Expert 3410 points

    Hi Sakeenah I proposed the following to the customer, however, they noted that the HDC2021 does not align with their previous RH % spectrum of 0-100%. I see that the HDC3021 does, however, the package is slightly different. Are these the main tradeoffs to consider?

    Additionally, my customer has reached out to me asking: for the original HDC2080DMBR that they are using, can you elaborate the details what would happen if water enters the exposed window of the sensor like during SMT machine wash?

    Is there a glass/ copper traces only or there is some sort of sponge medium inside the window that would hold the liquid until it evaporates?

  • +1 in reply to Abigail Leonardi
    TI__Expert 3385 points

    Hi Abigail,

    HDC2021 and HDC3021 are both I2C, however note they are not software compatible. HDC3x series does have an improved RH accuracy spec, so I would recommend it over the HDC2x series. The HDC302x Silicon Users Guide has a comparison table https://www.ti.com/lit/ug/snau265d/snau265d.pdf 

    The sensing element uses a polymer whose dielectric constant changes according to the ambient RH. It must be exposed to ambient air to properly measure RH. If a water drop occurs in the sensor cavity of HDC2x, then the RH measurement will suddenly spike then drop to 0%. It remains at 0% until the water is dried off. I copied an example graph from a little experiment I did with an EVM. 

    Best,

    Sakeenah