Is it possible for this NFET to go short from Drain to Source but not look damaged?

[treez]

Hello,
Is it possible for a DPAK FET to die by going short circuit from drain to source, (due to an overvoltage on its gate) but without actually exploding or looking damaged?

We have a 40W offline LED driver which has a current clamp FET, M4, in it which limits transient overcurrents. (as in the schematic attached).

We are worried that the zener diode D21, is sometimes soldered on but with a dry jointed anode connection, and therefore when first powered on, the NFET , M4 (M4 is actually a DPAK) gets an overvoltage between Gate and Source, and then dies and goes short circuit from drain to source, and just stays short circuit, without exploding.

Is this at all likely to happen?
If it does , then we have got no current clamp protection in our product.

 

[CataM]

I think that depending on the overcurrent level, before D21 has time to turn OFF, there will be an instant where the Vsg can be > than the maximum permissible level (30V). That would happen if voltage across R1 - D21 voltage when still ON is higher than the maximum source to gate permissible level.
That instant is the turn on time of the BJT active turn off switch.
You would need about 40 amps for that to happen.

 

[E-design]

How and when MOSFETs blow up

A typical failure mode for a MOSFET is a short between source and drain. In this case, only the source impedance of the power source limits the peak current. A common outcome of a direct short is a melting of the die and metal, eventually opening the circuit. For example, a suitably high voltage applied between the gate and source (VGS) will break down the MOSFET gate oxide. Gates rated at 12 V will likely succumb at about 15 V or so; gates having a 20-V rating typically fail at around 25 V.