A10 FPGA allowed maximum Mechanical pressure when mounting heatsink?

Hi,

we use A10 GX(10AX057H3F34E2SG) , FBGA package 1152 pins.

Desinged ONE whole large heatsink mounted on the top of 3 pcs of A10. Power is 20 Watt for each one, and we use compressible thermal pad for interfacing material placed between case top of A10 and metal heatsink.

When mounting, we must add certain pressure to keep the thermal pad contact with IC surface tightly to ensure the good thermal conductivity.

So what is the recommended Mechanical Pressure for A10 BGA ? (unit is MPa or PSI ,Pounds per square inch ), or what is the pressure limit so as to keep IC from being destroyed by over stressed, as well as avoiding long term crack of BGA balls.

I think mechanical characteristic of this kind of BGA packages might be similar , independent of specific part number, but I not sure of this, because different manufacturer may have difference. So I hope Intel expert could give some suggestions. A similar device of Xilinx is recommend to use 20-40 psi pressure. Any comments are welcome.

For Intel, I found this link, but not sure where to confirm the material of our part is SnPb (tin-lead) balls or SAC (tin-silver-copper) . Also not sure whether this informationn applies to all Intel FPGA.

https://www.intel.com/content/www/us/en/programmable/support/support-resources/knowledge-base/solutions/rd04172001_4367.html

Thanks