Friends - I'm "nearly done" with a six-layer design using pcb. I have assumed all along that the layers come in triplets, so with two ground planes every trace is close to ground. Nominal dielectric thicknesses would be 5+5+30+5+5 mils.
Following this group's lead, I have investigated Advanced Circuits as a possible board fabricator. While they say they can do almost anything in production, their prototype service has only a few six-layer stackups available, none of which come close to my concept. http://www.4pcb.com/service_circuit_boards_online_instant_dieletric_stackup_6layer.htm What they do have is a 0.045 laminated thickness board with three doublets. Approximate dielectric thicknesses are 4+14+4+14+4 mils. With some effort, I could adapt my layout to this stack. It would mean squeezing down my use of the one inner routing layer, and turning most of it into a ground plane. That way the inner power plane has an adjacent ground to form the other half of a capacitor. My question to this group (thanks for your patience) is whether this Adv.Cir. six-layer stack is typical for the industry? Or are there just as many companies out there for whom my original concept is standard? I think I read that commodity motherboards have recently moved from four layers to six. What's their typical stackup? - Larry
