MOSFET Short Circuit Failure — Root Cause & 8D Corre...

Symptoms Rds(on) near zero (dead short); gate oxide rupture Crater/burn mark on package; fuse blown Affected Components Power MOSFETs (Si, SiC, GaN) in drives, DC-DC, inverters Gate driver ICs; PCB switching loops Detection Methods Curve Tracer: Vgs(th), Rds(on), BVdss X-Ray/CSAM: Die attach voiding, wire bond lift-off Decap + Microscopy: ESD damage, hot spots Double Pulse Test: Vds overshoot, gate ringing, dV/dt Possible Causes Vds overvoltage: parasitic ringing exceeding BVdss Vgs overvoltage: gate ringing >±20V from Miller effect ESD: HBM/CDM during handling Thermal runaway: Rds(on) positive feedback Shoot-through: HS/LS simultaneous conduction dI/dt induced turn-on: Miller capacitance parasitic turn-on 5-Why Example Problem: Low-side MOSFET short during regenerative braking Why short? → Vds avalanche breakdown Why overvoltage? → Ringing 135V on 100V MOSFET Why ringing? → 25 nH parasitic inductance in DC-link Why uncontrolled? → Digital engineer reviewed, not power specialist Why wrong reviewer? → Design review checklist lacked power electronics requirement TRC: Parasitic inductance ringing causing overvoltage failure MRC: Design review didn't ensure power electronics specialist review Fishbone (6M) Man: No power layout expertise Machine: Capacitor 40mm from MOSFET Method: 2.2Ω gate resistor, no snubber Material: Eas=50mJ marginal for operating condition Measurement: 25°C waveform only Environment: Regenerative braking elevating DC-link to 85V...