HDC1080: /HDC2021: Vapor phase reflow possible on HDC2021? Is reconditioning required?

Hi A.

AnBer said:

So Vapour phase reflow might not be suited for HDC1080.

Since HDC2021 has a protective cover can it be soldered via vapor phase reflow soldering (see here)?
I saw some answer for IR reflow on this E2E post but nothing specific about vapour reflow:
https://e2e.ti.com/support/sensors/f/1023/p/929347/3434570#3434570

I saw as well some other post saying that HDC1080 could be protected with a polyimide tape:
https://e2e.ti.com/support/sensors/f/1023/p/898444/3321258#3321258
Would it work for vapour reflow or just for IR reflow?

Vapor phase reflow is generally not suitable for our humidity sensors, as that thread said the PFPE fluids will likely cause issues with humidity sensing elements. We do not have data with the HDC2021 and vapor phase reflow. The assembly protection tape may be enough to protect the sensing polymer from contamination, but we do not have enough information to say that definitively. We have only tested these parts with IR reflow processes. For the HDC1080 the answer would be the same, but with the additional variables of the quality of the selected PI tape, and the quality of the application of the PI tape.

AnBer said:

- reconditioning:
Some sensors do require to be heated to a certain temp for a certain time after PCB manufacturing in order to remove trace of humidity (ie reconditionning) so that the sensor get an accurate sensing level.
Is it the case for the HDC1xxx/HDC2xxx family?

No additional baking or high temperature curing is required for the HDC1x and HDC2x after reflow, but the HDC1x and HDC2x family do have a "settling time" after reflow, where they should be left at ambient conditions to recover from the reflow process. During that time the RH accuracy may be out of specification. Section 10.1.1.2 of the HDC2021 datasheet discusses this.

AnBer said:

I have read the below answer:

https://e2e.ti.com/support/sensors/f/1023/p/597300/2199422#2199422 
Does it means that reconditioning is needed after soldering only when water-wash process is applied?

The App Note SNIA025 does warn about cleaning agents such as PCB board wash agents.
Can there be risk with water-wash process that some chemical from solder paste or process might flow to the sensor?

In the case of the HDC2021 the board wash process should not be an issue, because the assembly tape protects the sensor. On all of our other humidity sensors we recommend not performing a board wash if possible. Instead a no-clean solder paste should be used to attach the HDC1x or HDC2x device to the board. If the board is washed a positive offset can be noticed in the sensing element that may or may not be recoverable using a high temperature bake and reconditioning.

Best Regards,
Brandon Fisher