Hi @AZ.2 ,
It is indeed one of most important and critical point of MEMS microphone handling, at leas before placing them inside a gasket housing, as happens in the common smartphones; but let me answer you point by point:
>> I would like to know if such restrictions are exist?
Yes, I confirm these restriction actually exists, especially if you have to treat microphones in an ambient with particles smaller than 100um size (the hole is about 350um diameter).
>> Is it safe to cover the porthole with tape and remove it after the cleaning?
It is important to cover the port hole with a tape, during the cleaning phase, for example with a kapton tape, especially if your cleaning at high temperatures.
It's not important to be full precise in the tape placing on the microphone top package, just be sure you covered the hole with a (clean) tape.
At the end of the cleaning, a good practice would be checking the hole through visual inspection (5x microscope would be enough) on a representative sample of production boards.
>> Maybe this component can be ordered with pre-mounted tape?
Unfortunately no, since it would imply an additional manufacturing step with some risk of contamination.
And I would suggest you to mount microphones together with the other components.
Let me please know if it can be helpful for your purposes.
-Eleon
