We have just disassembled the chip of Xeon Phi 7120 series many core coprocessor.
The Xeon Phi card was donated to us after it stopped working.
The size of the die was very large at 720 mm2 (22.5 mm × 32.0 mm).
We thought that the heat spreader was soldered to the die, as that's what Intel has been doing on their high-end processors for a while.
However, on this instance of Xeon Phi, there was silicone grease between the heat spreader and the die.
As we knew that the card was not working at the time we received it, we removed all capacitors on the package before cutting the adhesive between the package and the heat spreader.
We used a heat gun for this task.
As we thought that the heat spreader was soldered to the die, we used the heat gun the whole time.
Here are pictures taken before the card was sacrifised: