Design PCIE impedance and PCB material

May I know what impedance of PCIE diff. trace is? I checked design guide is 85 ohm, but developer kit is 90 ohm.

For PCB material, can I use EM-370(5) on PCIE Gen4 speed? However, I check the P3509_A01_PCB_stack up
P3509_A01_PCB_stackup.pdf (221.8 KB)
, the material is EM-370(5). If not, what kind of PCB material I can use?

Hi, please follow Design Guide for it, there is +/-15% tolerance on impedance. The PCB material option is to fit the impedance request of signal, so please follow the GEN4 routing guide in DG to select that.