what is ‘electromigration’ for us non-EEs ?
FYI: electromigration
This is a condition where someone wired up the transistors on one or multiple signals with a metal width too narrow to handle the current load. I/O signals normally are high current and need special attention.
The electrons flowing actually can bump copper atoms around to a point where the circuit opens and thus fails. The problem is magnafied with uni-directional current flow.
Usually there are checks in the process to prevent this from happening but its not uncommon to miss it.
Extremely small metal traces can give rise to microscopic-scale electric field strengths and current densities that are surprisingly large.
This makes the metal atoms actually migrate out of their original locations, and can even create shorts between adjacent conductors.
At the fine-scale geometries currently necessary, it doesn’t take a whole lot of metal or semi-metal atoms migrating to create a fault.