Can freezing/ice damage the BME680 pressure sensor?

[ThLOCP]

Dear Bosch Sensortec community,

Ou product embeds one BM680 with which we have carried out temperature and humidity test series in oven. Here are the test steps: (1) 70°C with 100%HR, then (2) a slow ramp-down from 70°C to -20°C with 100%HR. Off course, crossing the dew point, drops of water were formed. After this test the pressure sensor has not worked ever since. Both temperature and humidity measurement from the BME680 still work perfectly. 

We believe water has entered the small hole of the pressure sensor, turning into ice and potentially damaging the pressure sensor.

Questions:

- Does this analysis make sense?

- Is there a way to avoid this problem? Any workaround to protect the sensor without disrupting the measurement of the pressure sensor?

We thank you in advance for your help.

Best regards,

Thierry

[BSTRobin]

Hi ThLOCP,

Could we know the following information from you:
1.How many BME680 have you tested, and how many BME680 have encountered the issues you reported?
2.What is the value of the data register you read when the pressure sensor is not working?
3.When you test, did the BME680 power on or off before you read temperature, humidity, presssure sensor data?
4.What is the temperature step and interval time for temperature adjustment when the temperature slowly drops from 70 °C to -20 °C?

[ThLOCP]

Hello,

Thank you for your response. To answer you:

1.How many BME680 have you tested, and how many BME680 have encountered the issues you reported?

Tens of them are currently mounted and running but only one (the first time) followed this temperature/humidity testing serie. Then, we stopped because we did not want to disrupt more units before knowing more.

2.What is the value of the data register you read when the pressure sensor is not working?

"4294944.888" after library function conversion but I suspect it returns 0xFFFFFFFF.

3.When you test, did the BME680 power on or off before you read temperature, humidity, pressure sensor data?

No, it keeps on being powered all the time. Periodic reading are done more or less every 30 seconds. Temperature and humidity keeps on working without issue.

4.What is the temperature step and interval time for temperature adjustment when the temperature slowly drops from 70 °C to -20 °C?

I am sorry do not have in hand the exact protocol but according to our real time readings we log, it is about 1H30 to go from 70°C down to -20°C.

Best regards

Thierry

[ThLOCP]

Hello,

Do you have any updates after my additional information in response to your questions?

Best regards,

Thierry

[ThLOCP]

Hello,

There is about 1 month now you asked us serie of questions and we answered you. Do you have any updates after my additional information?

Best regards,

Thierry