Case 1821 ยท Public preview
Secondary Reflow Can Separate an Internal PTH Connection
A backplane circuit was open between two connector pins after local solder rework.
Continuity isolationOptical microscopyControlled excavationMicrosectioningSEMCircuit-path verification
What the evidence preview establishes
Thermal-mechanical overstress during secondary reflow or rework separated an internal layer connection from its plated-through hole. The same event rotated lands and fractured nearby copper and laminate.
Why this case matters
After localized rework creates an open, trace continuity to the internal layer and section the PTH. A visually acceptable surface joint can conceal land rotation and internal separation.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, four interpreted figures, alternative explanations, limitations, and practical application guidance.