VL53L0X Assembly Soldering Problem

[fafeyto]

We have a product(PCB) in mass production as using VL53L0X.

There is a problem with some of our products.

We tested before sending customer. There is no problem. But, over time we have received complaints from customers. In this case, We can't communicate with VL53L0X.

I want inspection report from the soldering company.

Can anyone explain and comment on the report? What is the meaning of gray circle that mentioned with red marked? Why are some small and some big? Could the problem I'm having be because of soldering?

I attached full report as a google drive link.

https://drive.google.com/file/d/1TuGtgAzskEg01juk0zyNGUpHgvrcmMKi/view?usp=sharing

[John E KVAM · Accepted solution]

That report sure looks to me like they X-rayed 33 parts and all of them looked good. So you do NOT have a production issue.

It has been my experience that one thing that can 'kill' these chips is noise on the I2C bus, leading to a situation of 'bus stuck low'. In an I2C bus, when not transmitting both the clock and the data lines are high. But if the host and sensor get out of sync due to noise on the line, the bus will get stuck low.

Another issue is that can arise is noise on the XSHUT line. Noise here will either cause a reboot or a partial reboot.

From that report I think I see the sensor attached to a cable. Cable length can be an issue with I2C.

But these issues just cause the device to hang. A restart should solve the issue. Is that the case.

If so, consider better decoupling caps, and stronger bulk caps. Stronger pull-up on the XShut line.

and of course get a good handle on the power rails.

If the sensor failed in such a way they cannot be rebooted, you would see burn marks in the x-ray. That does not appear to be the case.

I'm guessing noise or an elecro-magnetic pulse is your issue.

• john