Steve,



It may end up being one of life's little unexplained mysteries.



David A. Douthit

Manager

LoCan LLC



==========================



Steve Gregory wrote:



>  Hi David! I guess the reason I call this strange, is because I've had

> rework performed on literally hundreds of these type of parts, with

> the heat sink in the top, and haven't seen this problem before. When I

> say hundreds, I refer to a situation where a part was installed on an

> assembly, don't want to name names, at three-per, and the assembly

> didn't work. The manufacturer of the device says there was no die

> change, but for some reason, earlier date-code parts worked fine. So

> we changed out all these parts....same design, heat-sink in the top,

> but never saw cracking like this. To emphasize, this was just one part

> that did this, but it was so strange...I had to share. -Steve Gregory-

>

>      Steve,

>

>      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

>

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