MEMS Microphone PCB Failure Analysis

In my previous post I showed how I tested my microphone boards with a little test fixture.   Here are close-ups of the failed microphone PCBs (or we often call them 'tabs', or 'coupons').

This definitely shows a weakness with my PCB design in the ground plane -- the ground plane only connects around in one small wire on the top.  This isn't good  -- for signal integrity or anything else.  But in this simple pretty low speed (3mhz) board, it's kind of irrelevant.  Unless the apprentice V-Score driver drives over exactly that little part of the ground path!

These photos show how 5 of the boards were broken.

And... here are a couple of bad ones where the microphone wasn't placed correctly during assembly.  They should have caught these before sending to me!