VL53L7CX clean room requierment

[SabinMimulici]

Hello,

We are investigating the VL53L7CX presence detection ToF sensor. In the datasheet its mentioned it needs to be mounted in a clean environment "The customer is advised to use a clean assembly process until a
protective cover glass is mounted." and the application note TN1532 "Recommendations for assembling dToF sensors without liners in an environmentally clean place" - states that the sensors should be mounted in a clean environment grade 1000.  Our manufacturer dose not have a 1000 grade clean room but he has 10000 grade. 

What would be the consequences of mounting the sensor in an 10000 grade environment ?

Thank you very much! 

[John E KVAM]

This is a hard question to answer. ST of course has over-specified the requirement. But it's out of caution that we do this. We know the sensor will not work as well if you get debris in the openings.

As a practical matter it would depend on time. If you did the wave soldering and placed the cover over the chip soon after it comes out of the oven, you would be fine with a 10,000 grade cleanroom. 

But if you soldered them and left them for a week or two off in the corner somewhere, you would possibly have a problem. 

I would suggest that if you could keep them as clean as you can within reason, for a short a time as possible you would be fine. 

After all, I have some VL53L7 boards sitting on my desk in an open office and they work fine after months of sitting there. But I only have one or two and you potentially have thousands. And if mine fail, I can just get another, but you will have un-happy customers.

Set up a process where you pull the liner off JUST prior to putting on the protective cover glass and be as clean as you can. 

- john