Case 2323 ยท Public preview
Package Warpage Can Stretch Acceptable BGA Joints into Solder Columns
Corner solder balls were pulled into elongated columns, raising concern about head-in-pillow defects even though the examined joints were metallurgically acceptable.
MicrosectioningSEMEDSSolder-joint height comparisonIntermetallic evaluationPry testing
What the evidence preview establishes
Package warpage produced the greatest solder-joint height at the BGA corners and stretched the corner balls into hourglass-shaped columns. The examined joints nevertheless showed acceptable wetting and developed copper-nickel-tin intermetallic, while the geometry increased susceptibility to head-in-pillow formation.
Why this case matters
A stretched corner ball is not automatically a failed joint. Compare joint height across the package and evaluate wetting and intermetallic formation, while treating package warpage as a design-level head-in-pillow risk.
Full evidence reserved for MEMBER and STOREThe complete case includes the evidence sequence, four interpreted figures, alternative explanations, limitations, and practical application guidance.