SNAU265C june   2021  – july 2023 HDC3020 , HDC3020-Q1 , HDC3021 , HDC3021-Q1 , HDC3022 , HDC3022-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1HDC302x Devices
    1. 1.1 HDC3020 in WSON
    2. 1.2 HDC3021 in WSON
    3. 1.3 HDC3022 in WSON
  5. 2Storage and Handling Guidelines
    1. 2.1 Exposure to Contaminants
    2. 2.2 Chemical Analysis
      1. 2.2.1 Saturation and Recovery Tests
      2. 2.2.2 Long-Term Exposure
    3. 2.3 Packaging and Storing
      1. 2.3.1 Assembly
      2. 2.3.2 Application in Extreme Environment
  6. 3Programming the HDC3020
    1. 3.1 Trigger-On Demand
    2. 3.2 Auto Measurement
    3. 3.3 Programming the CRC
      1. 3.3.1 CRC C Code
    4. 3.4 Condensation Removal
    5. 3.5 Offset Error Correction
      1. 3.5.1 Offset Error Correction Example With a Fingerboard
  7. 4References
  8. 5Revision History

2.1 Exposure to Contaminants

Humidity sensors are not standard ICs and therefore must not be exposed to articles or volatile chemicals such as solvents or other inorganic compounds. The opening in the package allows the sensor to sense the relative humidity in the air, but also exposes the polymer to the environment, making it susceptible to pollutants. Typical ambient conditions do not present a significant risk for chemical exposure but manufacturing and storage environments are a known source of volatile contamination. During assembly, a Kapton tape can be placed over the sensor opening to ensure that the device is not exposed to harmful chemicals. The HDC3021 is great for applications where the chance for chemical exposure is high since it comes with a factory installed kapton cover. The tape can be removed after this process, but the device is still susceptible to contamination.

Exposure to a range of chemicals must be avoided or minimized. Exposure of the following chemicals is known to cause drift of the humidity output readings which may be irreversible:

  • Solvents such as:

    • Toluene: C7H8

    • Acetone: (CH3)2CO

    • Ethanol: C2H6O

    • Methanol: CH3OH

    • Isopropyl Alcohol: C3H8O

    • Di-isopropyl Ether: C6H14O

    • Ethylene Glycol: (CH2OH)2

    • Ethyl Acetate: C4H8O2

    • Butyl Acetate: C6H12O2

    • Methyl Ethyl Ketone: CH3C(O)CH2CH3\

  • Acids such as:

    • Hydrochloric Acid: HCl

    • Sulfuric Acid: H2SO4

    • Nitric Acid: HNO3

  • Other chemicals, including:

    • Ketenes

    • Ammonia: NH3

    • Hydrogen Peroxide: H2O2

    • Ozone: O3

    • Formaldehyde: CH2O

Such chemicals are an integral part of epoxies, glues, adhesives, or reaction byproducts that outgas during baking and curing processes.

The sense layer must not have direct contact with cleaning agents such as a PCB wash after soldering. Applying cleaning agents to the sense layer may lead to drift of the RH output or even complete breakdown of the sensor. Avoid strong blasts from aerosol dusters and use only low-pressure, oil-free air dusting.

If it is necessary to expose the HDC to contaminants, concentration and exposure time must be reduced as much as feasible. Good ventilation (fresh air supply) aids in lowering the concentration of volatile chemicals, particularly solvents.