A Hard-Shorted IGBT May Show No Visible Die-Surface Damage

H-bridge modules failed in relation to a reported system power-up sequence. Three examined modules had shorts among all three IGBT terminals, strongest between collector and emitter; their SCR sections appeared functional.

Electrical resistance testingGate-bias observationChemical decapsulationOptical microscopySEM

What the evidence preview establishes

Current overstress was the report's most likely explanation for the shorted IGBTs. Die-surface examination did not reveal metallization damage or fused silicon that would support a visible overvoltage event, but the internal collector-emitter junction was not deprocessed.

Why this case matters

Correlate terminal measurements with die inspection, but recognize the limits of a clean-looking surface. Reconstruct gate drive and current during the actual power-up sequence before assigning a specific electrical overstress mechanism.

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