Re: [TCML] New SISG failure mode

[sparktron01@xxxxxxxxxxx]

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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