Integrating Hybrid Electrical Test Regimes to Eliminate Unreached Structural Boundary Defects
Integrating hybrid boundary scan and flying probe regimes eliminates unreached structural defects by establishing 99 percent nodal fault coverage.
Solder Micro-Cracks
Material Fracture
Tiny fissures within a solder joint can grow over time and eventually cause a complete electrical failure of the circuit. Solder micro-cracks often start at the grain boundaries of the alloy due to mechanical stress or thermal expansion mismatch. These defects are frequently too small to be seen with the naked eye.
Development Mechanism
Development of solder micro-cracks is driven by repeated cycles of heating and cooling during the operation of the device. Lead-free alloys are more brittle than traditional tin-lead solders which makes them more susceptible to this type of damage. If the board is subjected to vibration or shock the existing micro-fissures can propagate rapidly through the bulk of the solder.
This process eventually separates the component lead from the pad or breaks the connection within a ball grid array. Early detection of these cracks requires high-magnification X-ray or acoustic microscopy because they do not always cause an immediate change in electrical resistance. High-quality flux and proper reflow profiles help create a more resilient crystalline structure that resists cracking.
Identification Outcome
Identification of solder micro-cracks during a reliability audit indicates a need for changes in the housing design or the thermal management strategy. Preventing these fractures is essential for long-term product survival.