Track where a broken copper trace goes after it disappears into the inner layers of the board.
If you've identified a cracked solder joint or a faulty component, the next steps involve advanced soldering. brittle mb 152561 boardview
Apply a minute drop of high-quality tacky rosin flux to the exposed copper sites. Tint the exposed pads with a fine-tip soldering iron heated to approximately 350°C using leaded solder (63/37 alloy is preferred for its lower melting point and flexibility on fragile boards). Track where a broken copper trace goes after