Hotplate Reflowing Fixes SPI Failure on Multiple LSM6DSO Breakout Boards

Sensors IMU & Motion
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In the last few months, we’ve purchased five [LSM6DSO breakout boards (SEN-18020) for evaluation. Of those five, four inexplicably stopped responding over SPI after a short while. Three of those four would function over I2C and one stopped responding altogether. After quite a bit of troubleshooting, we noticed that applying physical pressure to the top side of the LSM6DSO IC package could allow it respond over SPI ([demonstration) and began to suspect a solder joint issue under these little LGA-14L packages. Sure enough, after reflowing the boards with some flux and a little hotplate, all four began responding again over SPI.

To troubleshoot this issue, I used a Teensy 4.0 and a [low-level Arduino sketch that queries the whoami register on the LSM6DSO via SPI and displays the result in the serial monitor.](Sparkfun_LSM6DSO/whoami.ino at main · RonaldThomas/Sparkfun_LSM6DSO · GitHub)](https://www.youtube.com/watch?v=bHTUv8OoSj0)](https://www.sparkfun.com/products/18020)

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Ronald, thank you for posting on the forums.

We will look into the issue and see if we can improve the QC process to better cause any SPI related reflow issues in the future.

If you had batch #s for the units you had issues with please provide them.

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Thanks, John! Where would I find the batch numbers?

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It should have been stamped on the packaging for the devices.

If you had any units that you have not repaired we would be interested in taking them back for inspection to understand the issue more thoroughly.

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It should have been stamped on the packaging for the devices.

We didn't think to hang onto the packaging (especially before they started failing), but we found one bag printed with batch #143866. Unfortunately, we don't know whether that bag belongs to the one module that hasn't failed or one of the four that did. On September 27, I sent an email to support@sparkfun.com with the two associated order numbers if that might help narrow down the timeline. We recently purchased two more units that are still in their packaging and their batch numbers are also #143866.

If you had any units that you have not repaired we would be interested in taking them back for inspection to understand the issue more thoroughly.

We've already repaired all four of the units that failed, but we have one unit in use that hasn't yet failed and two new ones still in the packaging. If any of them do end up failing, we'll definitely let you know before attempting a reflow.