We have sensors failing because of what looks like dust or debris that is getting on the sensor.
Also, often it is difficult to detect and remove the Kapton tape covering the sensors. The tests we run pass even though the film has not been removed sometimes. This is a problem because there are performance issues later on that are easily fixed by removing the kapton tape.
A blast of air from one of those compressed air cans is the best way to do it.
We suggest a coverglass made of Acrylic, PMMA, Polycarbonate, or glass.
There is an article I wrote on this subject at the top of this community page.
I'd give that a read.
Thanks for your reply to my question.
One of my questions was not clear. When we purchase the sensor, it comes with a clear protective Kapton film on it. Due to the fact that it is clear, it is difficult to detect by the naked eye or simple vision systems. Also, the sensors pass our functional tests with or without the Kapton tape. Do the sensors come with an opaque protective film instead of the clear kapton film? If not, is it possible for ST to create a variant with an opaque protective film as an option? The opaque film will be easier to detect during functional testing and we will not need to rely on the human eye.
That tape is the only thing we could find that would survive the required 3 re-flows that the cellphone vendors demanded. There is nothing opaque that would do this and not leave a residue on the sensor. Sorry about that. I know it's a problem.
Imagine our dismay when a pre-production run of 100 cell-phones had to be dis-assembled because they left the tape on.