We had the top pop off of a VirtexII-Pro 2vp70 (1704BGA) and need to reattach it. The board and FPGA work fine. For some reason, Xilinx is refusing to tell us how to reattach the top correctly. Help please. What is the proper type of glue and the procedure?
Mike,
That is because there is no known way to re-attach it.
If it fell off because we did something wrong (quality, assembly fault, etc.), request to RMA the part, and we will replace it under warranty.
If you removed the top, then you have violated any warranty, and you need to get another one.
Sorry, but that is the simple truth.
"All the King's horses, and all the King's men, couldn't put Humpty Dumpty together again..."
The lid is a heatsink, and detaching it may have (usually does) damaged the die, and certainly can not be replaced such that Xilinx is able to stand behind it. We don't do it ourselves. We don't ask anyone else to.
I hope you can appreciate this,
Austin
mike_la_jolla wrote:
Mike,
It's really no big deal. Apply a dab of silicon grease (or equivalent) to the top of the die, but be very careful as this chunk of silicon cracks very easily. Apply some epoxy (or similar -- like E6000) along the top edge of the plastic case (that surrounds the little pcb and die). Now, just replace the little metal lid (the heat spreader) that popped off.
Bob
Some of the assembly epoxies are listed here:
And a side view of the heatspreader package assembly is here, along with cautions about applying shear forces to the lid:
If this is just a lab board you want to keep running, Bob's advice sounds fine to me, but I wouldn't ship anything with a reworked lid.
If you're drawing lots of power, note that the re-epoxied heatspreader may not work as well as the original.
Another possibility (if low power) would just be to glop a suitable encapsulant over the exposed die to protect it.
Brian
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