Just route power as a signal. Maybe a really fat trace / signal but it's still a signal.
Power planes are overrated especially for 100mA designs. If you are running a 500Amp GPU obviously you should consider a power plane but what kind of designs are people doing here?
EDIT: 10 Amp on 1oz according to first trace width calculator is supported by 20mm or 300 mil trace width. There's no reason to have a full power plane on amperage grounds.
And if you need board capacitance for your design to work then yeah, Power Planes can be useful for that. But only the highest of frequency circuits (think GHz+) seem to require those.
And if you do use Power Planes, then return currents may be induced on the Power plane instead of the ground plane, which is bad and hard to think about. (Power Planes cannot be shorted to Ground, meaning your return current needs to go across a high inductance via, into a capacitor, through to the ground plane where the return current should have been in the first place).
---------
Basically, power planes are one of those things that work at 50MHz just fine (enough random capacitors that magically transfer signals to the ground plane). But much above that frequency and those capacitors look more like a parasitic inductor. 500MHz signals will NOT go through a 100nF 0402 cap, that thing is practically an indicator by those frequencies. So it's not like power planes are easy to use.
The people who 'Need' a power plane are doing far more complex designs than the vast majority of board designers. And if they really need it, then they are using complex FEA simulations and calculations of PDNs that far exceed the scope of the level of advice in this topic.
> EDIT: 10 Amp on 1oz according to first trace width calculator is supported by 20mm or 300 mil trace width. There's no reason to have a full power plane on amperage grounds.
Power planes are overrated especially for 100mA designs. If you are running a 500Amp GPU obviously you should consider a power plane but what kind of designs are people doing here?
EDIT: 10 Amp on 1oz according to first trace width calculator is supported by 20mm or 300 mil trace width. There's no reason to have a full power plane on amperage grounds.
And if you need board capacitance for your design to work then yeah, Power Planes can be useful for that. But only the highest of frequency circuits (think GHz+) seem to require those.
And if you do use Power Planes, then return currents may be induced on the Power plane instead of the ground plane, which is bad and hard to think about. (Power Planes cannot be shorted to Ground, meaning your return current needs to go across a high inductance via, into a capacitor, through to the ground plane where the return current should have been in the first place).
---------
Basically, power planes are one of those things that work at 50MHz just fine (enough random capacitors that magically transfer signals to the ground plane). But much above that frequency and those capacitors look more like a parasitic inductor. 500MHz signals will NOT go through a 100nF 0402 cap, that thing is practically an indicator by those frequencies. So it's not like power planes are easy to use.
The people who 'Need' a power plane are doing far more complex designs than the vast majority of board designers. And if they really need it, then they are using complex FEA simulations and calculations of PDNs that far exceed the scope of the level of advice in this topic.