[SI-LIST] controlled impedance requirements

Hi gurus

How do you specify to the PCB manufacturer the controlled impedance 
requirements

Except the layer stack up, layer thickness (oz), board thickness and 
text that define the controlled impedance for signals in each layer
do you also define the PCB material type (Er, Silkscreen, Solder
=85), inner dielectric thickness or you trust the manufacturer to
reach the controlled impedance? 

How much tolerance do you permit? 

Thanks in advance
Kobi




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