Phil
I suspect you exceeded the pulse discharge rating of the die, and it did...
According to experts at several conferences I attended several years ago
failure of IGBT's at extreme pulse levels is roughly related to i^2*t rating
of die. Most Icm measurements are based on (1) pulse or repetetive
switching pulses. I've seen 1ms, and other time bases used.
Be careful when wading through the spec sheets...
Best Regards
Dave Sharpe,TCBOR/HEAS
Chesterfield, VA. USA
-------------- Original message ----------------------
From: FIFTYGUY@xxxxxxx
Folks-
I was going over the rest of my SISG to see how many replacement SIDACs
to order *this* time (note to self: buy stock in Littlefuse). Previously
damaged sections either had both the IGBT and all the SIDACs blown, or recently
just the SIDACs. So I had figured it was the SIDACs dying first that took out
their IGBT.
But this time I found a damaged section that had good SIDACs, but a
blown IGBT! Even more significantly, the gate was still at a high resistance to
the body, and I observed its capacitance charging up from the digital
multimeter. But the emitter and collector were dead shorted!
My guess is that this IGBT suffered from secondary breakdown. Does that
make it an IGSS now? (Insulated Gate Silicon Shunt). All other components in
that module appeared and measured perfectly fine, including the TVS's. Could
this be the result of excessive pulsed current or overheating?
(Note to self: buy stock in International Rectifier...)
-Phil LaBudde
Center for the Advanced Study of Ballistic Improbabilities
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