I2C copper trace lost continuity

[shredder929]

I have a unit that's been operational for a little over a year. Something went wrong and suddenly the LCD is no longer getting the I2C clock signal. Shorting the LCD's pin directly to the I2C SCL pin of another chip gets it working again.

I found a discontinuity between a via underneath the MSP back to the MSP pin. Everywhere else on the line has continuity.

At first I thought maybe the via wasn't properly connected all the way through the board. I lifted the MSP off the board and the via is fine. I carefully scratched off the solder mask and saw part of the copper trace has just vanished. You can see the discontinuity in the middle of the first image linked. The trace to the pin is fine, the via is fine, everywhere else is fine, but between that via under the MSP and the trace to the pin there's a small but clear discontinuity of no more than 25um across the entire width of the trace.

Has anyone seen something like this with a clock line? Trace width is 8mils, should be okay, it's been working for a year. Is this a one-off manufacturing defect, or a likely error in design/manufacturing that I can avoid?

Any and all advice/help is appreciated, thanks in advance!

Link to images

 

[betwixt]

I would say a one off problem and not in any way related to the function of the line. Most likely there was the thinnest of copper there due to contamination on the original copper board and moisture or other contaminants has eaten it away.

Brian.

 

[lhademmor]

Very bad manufacturer. They should have found this under aei. Could be but a bit unlikely, acid that was not properly cleaned of. But that would explain why it worked for years.