[SI-LIST] Microstrip vs. Stripline

  • From: Ravinder.Ajmani@xxxxxxxxxxxxxx
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Fri, 17 Sep 2010 14:28:37 -0700

Hi Experts,
I have 2.5" long interconnects running at 6 Gbps.  Currently I am using 
Microstrip transmission lines, routed over 3.5 mil Prepreg,  because I am 
able to route them on the Top layer without any vias.  However TDR shows 
impedance discontinuities perhaps caused by non-uniform plating and solder 
mask, and weave effect. 

I would like to know if a dual Stripline transmission line will be better 
although I will have to use a pair of vias on each trace.  My card 
thickness is 0.8 mm and back-drilling of the vias is not an option.  I 
also have to stay with standard FR-4 for cost reasons.  I have tried 
simulating both options and the simulation supports the Microstrip 
approach, but I am not able to simulate the effects of non-uniform plating 
and solder mask or weave effect.

Any suggestions.


Ravinder Ajmani
Server PCB Development
Hitachi Global Storage Technologies

Email: Ravinder.Ajmani@xxxxxxxxxxxxxx

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