Re: melting through 2901s?

Ok, so it's safe to assume those chips (and most likely the boards) are
dead? Good purchase on my part... ;)

So, another reason to not have back doors on games!

tm

Clay Cowgill wrote:
>
> >I've got a couple of Tempest aux boards that have AMD 2901s that seem to
> >have been melted through to the chip center. There is a Battlezone aux
> >board on eBay right now that shows the same characteristics.
> >
> >http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=556670453
> >
> >Is there any reason for this?
>
> I don't think it's a "melting" as much as explosion damage. ;-)
>
> If the die in the chip carrier fails in a sufficiently spectacular way it'll
> basically turn into a little space heater. The die area will get extremely
> hot (very quickly) and the plastic DIP carrier can't dissipate the heat
> quickly enough. The result is usually the carrier "blowing open" leaving a
> little crater-shaped hole in the top of the package.
>
> I actually had a 74xx series chip do that on a Pole Position board and it
> kept on cooking-- burned the chip down to the leadframe and pretty-much
> evaporated about a 2"x1" section of the PCB.
>
> Old process chips (like original 2901's, 74xx chips, I/O driver chips, etc)
> used relatively big die at the time, and could actually generate enough
> internal heat to fracture the chip carrier. You see "blown" transistors do
> that sometimes too-- literally blowing apart...
>
> -Clay
> (Yes, a post by Clay. I'm not dead. ;-)
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Received on Wed Feb 7 17:48:36 2001