stackup

[[email protected]]

hello every one . i have 8 layer stack up(top & gnd1 & sig1 & pwr1 &pwr2 &sig2 &gnd2 & bottom) . in this stackup the pwr1 and pwr2 are far from gnd layer. i wanted to know that the pwr layer should see the refrence (gnd) or it doesnt want?i mean that is it important to put a gnd layer top of pwr layers?

[qdrives]

Do you need 2 power layers?

[[email protected]]

yes .because we have many powers

[Paul van Avesaath]

looks like a solid layerstack to me, but be aware that if you have "noisy" voltages on the planes that would impact the signals on your midlayers.. so you have to take care when routing on these layers..

[qdrives]

Many powers does not necessary mean many (2) power layers. I too have many different power, but all are routed.
It is like Paul van Avesaath mentions, it the power is noisy, it will couple onto the signals, as the only returns for the power are the gnd layers opposite signal layers.

[robertferanec]

Be sure, dielectric 2 an 6 are thin (much thinner than Dielectric 3 and Dielectric 5). Also, depends on what you are going to route on this.

I recommend to watch this video - Rick is talking exactly about your stackup here: https://youtu.be/52fxuRGifLU?t=3242