FEDEVEL
Platform forum

zeino , 02-15-2016, 12:18 PM

@robertferanec From EMI stand point I understand that having two GND planes and making a Faraday Cage and the signaling in middle is a better way just like the Video. Also I understand that if having voltage plane we better put it close to the GND plane if we are going to have it as a plane. Why did you make the VCC a plane at the end and not associate a plane to it when planning the layers. Does it have a practical reason or just to teach us how to select using the filter or is it because we only had 6 planes and you wanted to be flexible?

Also when building Embedded boards what is your layer number preferences and how do the layers look like. I would appreciate if you share your expertise on this.

robertferanec , 02-16-2016, 07:01 AM

You can set VCC as a plane. I found it easier to work with Polygons, rather then using planes, so I do it that way. I use planes only for full solid GND.

About the layers ....this may help you: 3 STEPS How to determine / calculate number of PCB layers

zeino , 02-16-2016, 09:29 AM

Thank you very much Robert, I wouldn't have an idea that 10 layers is more popular. This is a great classification. I think I will use the method described in step 2.So memory and interfaces are one aspect of it. I guess I need to hurry up and finish the 2nd course. I think for my board I would need to do 10 layer with what I read as it will have memory and LVDS.

One thing that intrigues me is the layer structure in 8 and above layer position of power plane. I thought it should be near the ground but at position between two paired signal layers, such power plane may be acting as a virtual ground for high speed signal, therefore shielding the signals it is separating form each other.

robertferanec , 02-17-2016, 08:19 AM

Some power planes can also be reference planes (e.g. if you have a lot of decoupling capacitors connected between the plane and GND, as decoupling capacitors are short circuits for high speed). And sometimes you don't have a choice