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Platform forum

robertjzima , 03-05-2018, 06:54 AM

Hello. I'd like to know your opinion about a stackup, I've received from the manufacturer. The board is going to be 12 layers as you can see from the stackup. My question is about power planes/polygons. I'd like to use L5 and L8 not as a signal, but as a dedicated Power layers with polygons only. Sounds that as a good approach to you? You're more experienced with stackups than me .

The interesting thing for me is that the manufacturer recommended L11 as a solid Power plane. I've never seen that before. This layer is usually GND. What's the best practice in this case. Should I use it as a dedicated plane for, let's say, most used power net? Thanks.

EDIT: Maybe another idea is to change internal GND on L6 and L7 to signal then I can use it for Power polygons. L11 then change to GND. Then it should be like this:

L1: SIGNAL TOP
L2: GND
L3: SIGNAL
L4: GND
L5,L6,L7,L8 - SIGNAL (POWER)
L9: GND
L10: SIGNAL
L11: GND
L12: SIGNAL BOTTOM


Regards,
Robert

robertferanec , 03-05-2018, 06:38 PM

I use this stackup what you are suggesting a lot. I just try to keep minimum number of signals routed in the power planes. Usually L5 or L8 (or both) are whole board power planes (e.g 3V3), other power planes are smaller local power lanes.