Gauges must be placed immediately adjacent to the corners of critical components (like large BGAs), as the corners experience the highest stress concentration during board warping. 2. The Strain Metrics: Diagonal and Principal Strain
If you acquire the official , here are the critical chapters you must study: ipc-9704 pdf
The IPC-9704 guideline provides specific methodologies to monitor and control strain. 1. Strain Gage Selection and Placement Gauges must be placed immediately adjacent to the