You might consider the fact that metal will change temperature much faster than polymers.
This thermal gradient "split" can cause serious temporary CTE mismatches.

David A. Douthit
Manager
LoCan LLC

Steve Gregory wrote:

Yep, got the tape and used it on this part...I've always used it on parts with a heatsink. The profile I had was basically the same profile I've used with a Analog Devices SHARC 240-pin QFP that has a heatsink in the top like this Altera part.

I wonder if I should be concerned with other parts from this lot, even if they've not exhibited the cracking like this one part did?

-Steve Gregory-
 
 

Do you have that Black TyveK tape? PDR gave us some for use with metal case components. I think that metal top may reflect more energy than the black plastic. I bet the temperature difference is enough to crack the package. It might be lot dependent, There is probably some variation in the actual thickness of the plastic over the metal spreader. I don't think this was due to moisture.

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