3 ms·

https://m.youtube.com/watch?v=60RxCiZuD9E https://m.youtube.com/watch?v=60RxCiZuD9E Rick Hartley explains.

• exmadscientist 2y ago
  I don't think you are arguing for the same thing as Hartley. I strongly approve of some things he says: "people believe that just pouring ground on top and bottom lowers EMI... well it doesn't!" (6:04) or "there is no four layer stackup that's wonderfu... no 'gosh, isn't that great?' four-layer stackup, they just don't exist, it's four layers, you know, you can only do so much with it" (7:29). No mention of VDD noise or discussion of how a good, well-decoupled power plane is basically as good as a ground plane for AC return currents. I believe you are trying to get a stackup that supports use of stripline for signals. That is a reasonable goal but it is only appropriate for very high speed digital designs. If you route stripline on a regular basis, you're either very experienced or clueless. No middle ground! Really, for heavy-duty work, you need six. And you can argue with me, and say that by great skill you can get things into four layers, and that is true. But six-layer boards are cheap compared to what they used to be, so for anything not going into true high-volume manufacturing, just go for six or eight. In all other cases, the design cost hit will outweigh the parts cost savings.