> 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.
That's a very odd stackup. Normally, they build a six layer board from 2 laminates (2 sides each) plus the 2 outer layers. The laminates are usually thicker than 5 mils. The outer layers are built differently from the laminates, which is why you can get the 5-8 mil thicknesses there. What you are describing is more like a 4 layer board (one laminate plus outer layers) with 2 additional outer layers on top. Matt
