Case 102 ยท Public preview
Lead-Finish Separation Can Expose Intermetallic and Prevent QFP Wetting
Multiple QFP leads contacted their solder deposits but did not wet during reflow.
Optical microscopySEMEDSMicrosectioningComponent and board comparison
What the evidence preview establishes
The bottom surfaces of nonwetted leads lacked their tin-lead finish and exposed copper-tin intermetallic, whose oxide is difficult to wet. Organic material incorporated during electroplating likely weakened the finish-to-base-metal interface and allowed separation or dewetting during thermal or mechanical stress.
Why this case matters
A nonwetted lead is not always a paste or board problem. Cross-sectioning the lead bottom and examining the finish-to-base-metal interface can reveal a component-plating failure hidden from surface inspection.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, four interpreted figures, alternative explanations, limitations, and practical application guidance.