SNAU265D June   2021  – February 2025 HDC3020 , HDC3020-Q1 , HDC3021 , HDC3021-Q1 , HDC3022 , HDC3022-Q1 , HDC3120 , HDC3120-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1HDC3x Devices
    1. 1.1 HDC3x2x Package Comparison
    2. 1.2 HDC3020 in WSON
    3. 1.3 HDC3021 in WSON
    4. 1.4 HDC3022 in WSON
    5.     HDC3120 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 The Functional Modes
    2. 3.2 Trigger-On Demand
    3. 3.3 Auto Measurement
    4. 3.4 Programming the CRC
      1. 3.4.1 CRC C Code
    5. 3.5 Example Code
    6. 3.6 Condensation Removal
    7. 3.7 Offset Error Correction
      1. 3.7.1 Offset Error Correction Example With a Fingerboard
  7. 4References
  8. 5Revision History

2.3.1 Assembly

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. Contaminants such as those listed in Exposure to Contaminants must be avoided or minimized. Maximum assembly temperatures and exposure times must not be exceeded. Wave soldering is not recommended. Avoid using ultrasonic cleaning after assembly, which can damage the sensor. Standard reflow soldering ovens are recommended. The HDC3x family uses the standard soldering profile IPC/JEDEC J-STD-020 with peak temperatures at 260°C. When using the HDC3021, wait to remove the polyimide tape cover until all assembly steps are complete, and before the rehydration step begins.

Rehydration is the process of reintroducing ambient moisture into the humidity sensor. It is recommended after assembly or if another baking step is taken. TI's current recommended rehydration condition is to leave the sensor unpowered at 25°C and 50%RH for five days.

If using conformal coating (for example, if water is anticipated in the application conformal coating is used to protect the PCB from electrical shorting), it is strongly recommended that the HDC3021 option is chosen (polyimide tape cover). The tape cover should be left on during the complete assembly process, including the conformal coating cure, then removed at the very end of the process. If another package option is chosen, conformal coating covers the sensor area. This has a significant negative impact on the HDC3x's ability to sense humid air, since the cured coating is covering the sensor area so humid air cannot enter the sensor.

Note: It is important that no-clean solder paste is used and no board wash is applied once the sensor is assembled onto the PCB. To ensure proper device performance, these instructions should be communicated to board manufacturers before assembly. Furthermore, when identifying a no-clean solder paste, look at the Material Safety Data Sheet (MSDS) of the product in question to ensure there are no chemical contaminants such as VOCs.

MSDS documents can usually be obtained on the product website or 3rd party purchasing site. If no MSDS is found or is publicly available, manufacturers should provide this document upon request.