Electronics360: "How to Protect Your PCBs"

I've had reliability problems with "glob top" chip-on-board encapsulation. Very often the circuit acts as if a wire bond between the chip and PCB has broken. I've seen this on alarm clocks with a vibrator, toys, and calculators that have been dropped, so it seems likely to be a shock and vibration issue. Avoid touching such encapsulations; it doesn't take much to break the wires.