Hello John,
Thank you for the reply. Let me explain the end use case.
We use the TOF sensor to find a delta in displacement. We are not very keen in knowing absolute distance with pin point accuracy. We also DONT use a covering glass or any sort to cover the sensor. In the end application, the sensor will be in an enclosed space, free of any one touching or fiddling with the senor. We need to reliably detect a change in distance of 2.0 mm. In the pilot batch of 50 boards, I had seen them detecting the delta of 2.0 mm.
In our present production flow, we do a PCB bring up and unit test. Here to make sure our sensor is not way off the mark, we do a distance measurement on a test jig. Here we have a retro reflector kept at 50 mm away from the sensor. Presently we keep 37 mm as minimum distance and 63 mm as maximum distance. We have ~ 130 boards (out of ~ 1800) that fall below the 37 mm readout. The +/- 13mm margin was decided based on a pilot run of 50 boards.
My concern is:
Will the sensors that reads less than 37 during unit test (the expected readout is 50mm) detect a change in displacement of 2.0mm.? Will a sensor that reads ~ 25mm instead of expected 50mm be able to detect our required 2mm delta?
The PCB's are built in our EMS factory and our assembly line is at another geographic location. We plan to take few samples out of the 130 boards and try out in our system to see if they can indeed detect the 2mm delta.
BTW, the PCB goes through a reflow cycle and a wave soldering cycle. The sensor is protected using special wave soldering PCB fixtures. Do you see this as a concern ?
BTW, attached are the images of the PCB with VL6180
Thanks
syam k
