> Does anyone know what the right silicone for bonding the pressure sensor
bare die on PCB is? How do I prevent the fracture and keep good adhesive?
[FLUFF TRIMMED]

Use an RTV (room-temperature vulcanizing) silicone from Dow Corning or GE,
such as RTV 730.
Young's modulus for RTVs is very low, so little (but not zero) stress gets
transmitted from the die to what it's mounted on.
I would caution you that the PCB probably has a much higher TCE than
silicon,
so thermal stress will be created as the temperature fluctuates, which will
give a false signal.
It is better to mount the die on something else like Kovar, then attach that
to the board.

    --Kirt Williams, Ph.D.  consultant