Connector Corrosion Failure — Root Cause & 8D Correc...

Symptoms Green/white deposits (Cu) or red rust (Fe) on pins Contact R 5 mΩ → 50 Ω; intermittent signal loss; pitting Affected Components Automotive connectors (engine bay, underbody); M8/M12 industrial PCB edge connectors; terminal pins (Sn, Au, Ag plated) Detection Methods Visual 10–30×: Discoloration, deposits, seal damage 4-wire Kelvin: Contact R vs spec (<10 mΩ) Salt Spray ASTM B117; MFG Test (SO₂, H₂S, NO₂, Cl₂) SEM/EDS: Corrosion composition, plating integrity Possible Causes Galvanic corrosion: dissimilar metals + moisture Fretting corrosion: micro-motion wearing plating Plating porosity exposing base metal; water ingress through seals Chemical exposure: road salt, engine fluids, industrial gases 5-Why Example Problem: CAN bus intermittent communication failure in engine bay Why intermittent? → Contact R 5 mΩ → 50 Ω on pin 3 Why high R? → Copper sulfate corrosion on terminal Why corrosion? → Au plating worn through, moisture entered Why moisture? → Silicone seal cracked after 3 years at 120°C cyclic Why unpredicted? → Qualified at 85°C continuous, not 120°C cyclic TRC: Moisture ingress through degraded seal causing copper corrosion MRC: Connector qualification conditions didn't replicate actual environment Fishbone (6M) Man: Pinched seal during harness install Machine: Tight harness routing, constant pull Method: No seal inspection at...