A PCB once designed shall be shared for manufacturing. Manufacturers uses the core and prepeg materials as available and achieves the stack up and thickness as desired. One of the common problems designers face is that when manufacturer is changed, performance changes especially with the high speed digital and RF designs. This is due to the prepeg combinations used by two different manufacturers and this changes the following:
- Signal travel speed (which we call time of flight)
- Trace impedance
To get common impedance between the PCB from two different manufacturers, the trace widths have to be adjusted from the value included by the designers. This is a major challenge faced by the designers.
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