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koreshx , 06-21-2016, 06:49 AM

Hello.
My pcb partner manufacturer can produce 6\8\10… boards. But prototype prices of 6 layers and 8\10 layers boards are differ dramatically. So I want to route 6 layers boards. It’s not a very complex board (it doesn’t contain many peripherals, only SoC, ddr3 memory, power and some interfaces).

I want to use stackup like this:
-Signals
-Plane
-Signals
---
-Signals
-Plane
-Signals

So what is your opinion – is it possible to use power plane (not ground plane) as plane for ddr3 signals? Is’ it possible in theory or is it absolutely wrong?
Can we use power plane instead ground plane as base cooper for microstrip high speed lines?

And one more question. May be somebody can advice free tool to layers stackup planning (with materials base). Unfortunately my pcb partner can't suggest to me optimal stackup template and I must calculate it myself.

Thanks!

mairomaster , 06-21-2016, 07:45 AM

We are discussing this topic here:


If your manufacturer can't provide you with a stackup and you need to do DDR3 routing, I would change the manufacturer.

koreshx , 06-21-2016, 07:48 AM

OK.
I've found ICD Stackup Planner....

koreshx , 06-21-2016, 08:15 AM

I've found the answer.

robertferanec , 06-23-2016, 07:36 AM

Be careful. If a PCB manufacturer can not give you the stackup and you have to do it by yourself, the final impedance may not be correct. Process of PCB manufacturing influence the "theoretical" stackup and the final values may be a little bit different (e.g. by heating up prepreg, it melts and final thickness may differ from the documentation value)