Case 1321 ยท Public preview
Nominally Good Joints Can Reveal an Under-Designed Fatigue System
Sensor terminal solder joints fractured in service, with extensive damage to solder, plated-through-hole barrels, pins, and surrounding laminate.
SEMEDSMicrosectioningFailed-to-surviving comparisonSolder-microstructure evaluationTerminal-plating review
What the evidence preview establishes
The solder joints were under-designed for the mechanical loads encountered in use. Cyclic terminal bending produced low-cycle solder fatigue, PTH-barrel fractures, laminate damage, and permanent joint distortion.
Why this case matters
Surviving joints are valuable life indicators. If supposedly good joints show the same early cracks and microstructural coarsening as failed joints, corrective action must address load path and joint geometry rather than repair isolated failures.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, four interpreted figures, alternative explanations, limitations, and practical application guidance.