Routing SATA and PCIe with traces under ground

[angelsix]

This will be my first time routing SATA and PCIe routes. Any advice in using altium to assist with the differential matching?

Also my main question, if I have a multi layer board, and I route SATA on top, PCIe on bottom, with ground just below each of those layers, and other signals in the middle of the board, are those signal wires in the middle OK to run past the SATA and PCIe routes as there is a full ground plane between them?

[robertferanec]

angelsix
- About diff pair routing, this may help you: Altium – Differential Pairs (The New & Old Way)
- You can route standard digital signals under PCIE and SATA, no problem

[angelsix]

Thanks. For the video you used a stackup document specifying the trace widths and gaps. Where do you get that or how do you generate that? Is it something specific to each PCB manufacturer, or is it defined by the layer stack you make in altium somehow? I need 100ohm for PCIe and SATA I think, and will be using 4 or 6 layer stack on 0.5mm board if possible, if not then as thin a board as possible. How do I generate the values?

[robertferanec]

Where do you get that or how do you generate that?
- you can design your own stackup or ask PCB manufacturer

Is it something specific to each PCB manufacturer, or is it defined by the layer stack you make in altium somehow?
- it is defined by stackup, which you or PCB manufacturer design

I need 100ohm for PCIe and SATA I think, and will be using 4 or 6 layer stack on 0.5mm board if possible, if not then as thin a board as possible. How do I generate the values?
- you will need to talk to your PCB manufacturer

I wrote couple of articles about impedances and stackup. Simply just search on my blog for "stackup": http://www.fedevel.com/welldoneblog/?s=stackup

[angelsix]

Thanks. I'm working with a PCB manufacturer now on the stack up. I've only done 2 layer boards before and how had to contact a fab house before making the PCB.

For the stack up, I've made one in Altium just to get started, but how do I generate the differential values for the rules wizard from the stack up? Is there an automated way in Altium to calculate those values and generate a stack up PDF with those values?

[angelsix]

Another quick question. I have a simple USB diff pair, the connector is on the bottom, the pins on the top.

Should I just use a through hole via, or should I step through each layer with micro vias?

[robertferanec]

angelsix if you are not sure, I recommend you to have a look on some existing designs. For example, you can use our iMX6Rex projects to check how we routed some tracks.

To answer your question: In high speed signals you want to keep minimum number of VIAs, however in important signals you need to consider also stubs in VIAs (e.g. if you use a through hole VIA to connect signals on L1 -> L3, then L3 -> L12 is a stub in VIA). In your case, I would just use through hole VIAs.